Actually, they do. In several comics (the second Vision and the Scarlet Witch miniseries comes to mind) make mention of a stipend for both active and reserve members of the Avengers, paid out via the Maria Stark Foundation (which Tony founded to insure the financing of the Avengers independently of his current finances; he is, of course, the first and largest patron to said foundation.)
That said, the usual mention of said reserve stipend was that it alone barely covered Vision and Wanda's bills, and that either they needed an additional source of income or for one of them to return to active duty after she gave birth. (She was pregnant with twins at the time.) So, not a lot for reservists.
As to the FF.... you are quite right; the majority of their problems originate from the team's resident mad scientist pushing boundaries that wiser men would have left alone. Not all, mind you; Doom can, ironically, be blamed on Ben, and Galactus would have shown up regardless; in that case, Reed racing to the moon months earlier ended up giving them a warning they otherwise would not have had.
As for Kang.... Reed didn't invent the Time Travel tech he used; he re-purposed Doom's device instead. So, just because the man who would be Kang found one of Doom's time machines in one of Reed's storage vaults doesn't mean Reed was at fault for locking up a dangerous yet useful piece of tech that a different mad scientist invented....
The stipend I believe is suppose to barely be enough to cover expenses, if you're staying at Avengers Mansion. I think one of the reasons Steve Rodgers keeps going on missions for Nick Fury despite
really disapproving of Fury's usual methods is because the good Captain quite honestly needs the money. Not that this has ever actually been mentioned, but you
know that Fury pays heroes for their work. In fact, this is a key plot point at the start of Sensational She-Hulk. Fury
hires She-Hulk to help shut down a gamma reactor.
Also, Doc Doom would have been a villain to begin with. That is true. He thinks he's the smartest person on the planet, and can run the world better then everyone currently doing so. And you know what? He might be right about doing a better job running the world. Crime and poverty are virtually non-existent in Latvaria. Then again, so are civil liberties and human rights. But the reason Doctor Doom constantly harasses the Fantastic Four has nothing to do with Ben Grimm. Instead it's because he blames Reed Richards for his horribly disfigured face. They were collage roommates, and Reed pointed out a mistake Victor Von Doom had made in a calculation. But of course Doom doesn't
make mistakes, does he? So he ignored the warning, and the experiment blew up in Doom's face. Oh noes! Since Victor Von Doom is
clearly the superior intellect and never makes mistakes, Richards obviously sabotaged the experiment. At least that was the original backstory. Not sure if it's been retconed since then.
As to Spider-Man being the cause of his own misfortune, that's actually true to an extent. He struggles to hold down a job because his over developed sense of responsibility causes him to constantly be late for work (due to stopping every crime he comes across). He gets kicked out of apartments because rather then paying the rent, he's buying chemicals to make more web fluid and fighting crime. He struggles with his relationships because he's constantly pulled away to stop some random crime or super villain. Gwen Stacy died because of his being Spider-Man too, but it wasn't actually his fault. Well, not entirely his fault. Green Goblin targeted her because he'd learned Spider-Man's secret identity. She was imperiled because Norman Osborn is a lunatic. If she'd been dating Harry Osborn and thus Norman thought she was getting between him and molding his son into the 'right sort of person' she'd still have been in danger. But her death was actually more due to Parker being a teenager who had never had to do anything like rescue someone falling from a great height before. And in his inexperience, Parker hadn't known how to catch someone falling in a way they wont suffer fatal whiplash.
Yes, I've read every single issue of Spider-Man from Amazing Fantasy #15 through the death of Gwen Stacy. And that was the first time Peter had tried to catch someone who was falling from a great height. Afterwords, I'd imagine he spent a lot of time practicing to avoid such a mistake occurring again. He also developed settings for his web shooters which let him create web-nets to catch people who were falling.
And while you might deride Peter Parker for causing so many of his own problems in life by being obsessed with being Spider-Man, you have to remember
why he has such an overwhelming sense of responsibility. When he first got his powers Parker had no intention of being a hero. He just wanted to make money, and maybe be famous as well. After his initial amateur wrestling debut he was doing the talk show circuit. His aunt and uncle were concerned about him without knowing what was really going on. So Uncle Ben sat down to talk with Peter. The last words Peter heard from his uncle was "you have great power, and with great power comes great responsibility". Now granted, Uncle Ben was likely referring to the fact that Peter was on the cusp of adulthood, was very intelligent, and had many potential paths ahead of him. Not that if you have super powers it's your responsibility to use them to help others. And Peter, teenager that he was, completely blew this off to continue his road to fame and fortune.
As we all know, a thief runs past Spider-Man after his latest appearance (in Amazing Fantasy #15 it was a talk show appearance), and a security guard calls for Spider-Man to stop the crook. Instead, he lets the nameless crook run by. Thus the crook manages to get away. And when called out on this callous and uncaring act, Parker's reply is "it's not my job". It's the two fold gut punch of his uncle's last words and the fact that his uncle was killed by the same man Peter allowed to escape because it 'wasn't his job' are why his life motto became "With great power
must come great responsibility." These events occurred during a critical time for Peter, he was maybe 14, 15 at most when he became Spider-Man. This was literally a defining moment. And that responsibility
does weigh Parker down heavily. He's tried to give up being Spider-Man many times over the years. But each and every time he's pulled back in to stop some super villain who the police are unequipped to handle and the other heroes are too busy to deal with.
And to be honest, without Spider-Man Earth 616 (and it's close analogs) would be a far worse place. After Onslaught the Avengers and Fantastic Four were thought to be dead. Which removed many of New York's heroes. So guess who had to step in to try keeping a lid on the
entire city? Yup, you guessed it. Your friendly neighborhood wall crawler was running himself to exhaustion and beyond trying to deal with his own rogues gallery
and any other villains that popped up that one of the Avengers would normally have handled.
EDIT: This is actually one of the things I think the newest Spider-Man game on PS4 gets right. The game actively encourages the player to stop every single kidnapping, drug deal, robbery, and mugging. Thus encouraging you to play the game like Peter Parker actually would behave if he had constant access to the police dispatch. And every time he's suppose to show up for work, he's late due to his activities as Spider-Man. In fact, often the game will give story objectives for you to do something as Spider-Man when he's
suppose to be going to work.
In fact, the game opens up with Peter waking up, realizing he'll be late for work if he doesn't hurry up and then spys the Past Due notice informing him that if he doesn't pay his rent
today he'll be evicted. Only for his police band radio to inform him that the police are about to try arresting Wilson Fisk. You can
see him agonizing over paying the rent or helping take down Fisk. Only for his sense of duty to kick in, and he goes off to battle a super villain instead of paying rent or going to work. Which is both a good and bad decision. He saves a lot of lives, but... Well... There's consequences.
In fact, even though he knows he's suppose to be going to work now the game's next few story missions are a lengthy bit of him being a hero. Thus making him late for work and leading to bad repercussions which are felt throughout the rest of the game. Hell, even during a (not)date with Mary Jane he's visibly torn when a police car drives by with the sirens going. Of course MJ sighs and tells him to go do his thing. And of course this makes him late for work
yet again. Leading once again to a string of bad events that could have been prevented if he'd just gotten to work on time.
This is a theme that crops up many times so far in the game, and I've not completed it by any stretch of the imagination. Peter does good work, saves lives, but his life is ruined by his obsessive need to stop every crime he comes across.
