I like to view this as us overestimating Dandeer's weak points(intelligence/skill/planning/competence), and underestimating her strong point(mind control magic hammer).
You would be survived at how stupid people can be, even otherwise "competent" ones. The number of hairbrained spy schemes is staggering.
But seriously, I think this is a good argument for "study the enemy". And "always make sure."
And "use our Sight more." Since one of the biggest ways our presumptions bit us in the ass was that we assumed we DIDN'T need to use the Sight to scry on the events of the Sealing ourselves, because Carrick Balor and the other seers were doing it for us. It's not clear to me that Carrick ever recruited the other Seers at all, as he said he would do. And if he did, well, he wasn't passing on the most significant of their reports to us. If we had put in even a modicum of effort using the Sight ourselves, we would have learned what was happening and without too much trouble averted it.
I think a better one is "never give anyone faith or credit unless they've explicitly earned it."
The thing is, when you're up against a mind controlling witch, it's entirely possible for people who HAVE done a great deal to earn faith and credit to abruptly change sides and screw us over.
Carrick Balor taught us essential skills that
at this very moment are the only way we were ever able to escape Dandeer's victory. Berra taught us the vast majority of what we know about fighting, and how to become a super-saiyan.
Both of these men are people who, in the normal course of things, would have been our strongest and most trustworthy allies and who would have saved us from many perils.
Because we were up against Dandeer, both of them were forced against their will to act as our enemies.
This is me speaking from real life study, but never underestimate the stupidity of people in or against conspiracies, they will always surprise and make you doubt the potential future of humanity.
True. I should have remembered my Cipolla.
Another part of that is the action economy at the time. It would have been a good idea to do a bunch of paranoid spy sweeps of all assets, on general principles if nothing else... But with the information we had, was that probable enough to be one of the ~10 things we want to do that year? It's not clear to me that that was a mistake even in hindsight, with the information we had.
I mean, the point kicking off this entire discussion was Gore noting that we could have spent ONE action sweeping our key co-coconspirators for Dandeer's mind control bugs. Given that Dandeer was the arc villain of the time, and mind control was her main known means of posing a threat, this would have been a pretty rationally directed use of our time.
And it would have been enough.
So the lesson can just as well be "focus on defeating one enemy at a time, and don't let your long term training priorities override the need to prepare against the specific individual being you're working to confront." Honestly we had enough time to do SOMETHING about this even in the limited time between beating Dazarel and the Unsealing, because something as trivial as "sweep Yammar for bugs" would have immediately revealed the problem.
The problem was, as you note, vote structure; we weren't given an open-ended opportunity to say "here are the list of things we want to do in the name of taking precautions," we were given a chance to vote yes or no on the details until the last minute... At which point the vote choice became "so, do you carry out the existing plan of your allies who you have no specific reason to distrust, or do you derail the train by doing something different?
[Bluntly, one of the reasons I am super disappointed in the pre-existing power structure among the Exiles is that no one besides us WAS pre-sweeping Berra for bugs, because the Gokuns had like over 9000 sorcerors even if they were hilariously overworked doing the work of their dead Vegetan counterparts for most of our lives.]
The lesson I take is "Don't trust anyone, do everything ourself, be (in character) bitter as hell."
This is a recipe for OTHER disastrous failure modes. Lots of them.
I doubt capsules had anything to do with gravity manipulation. In 'Jacko the galactic patrolman' Jacko meets the Brief family when Bulma was 5 or so. Jacko's ship was broken so he lets Mr Brief examine it; while doing so he comments that it is impressive that the ship flies by manipulating gravity and Jacko lets him study it because it is an old model and not that impressive. Presumably, flying cars and the gravity chamber are derivates from that tech.
Likewise, FTL is probably derivated from the several space ships they had the chance to study (Nameless Namekian's, Goku's and Jacko's)
To clarify what I meant, I'm saying that capsules and gravity generators may involve
the same physics, in the same sense that, e.g., electric generators and radio antennas use the same physics (Maxwell's laws of electricity and magnetism) despite doing entirely different things.
Based on what we know about the real universe, which is
admittedly questionable in the context of Dragonball...
Gravity IS, at a deep level, a force that distorts space and time.
When you sit on the surface of the Earth, you feel gravity towards the center of the Earth because spacetime has been distorted. In stronger gravitational fields (say, inside the event horizon of a black hole), falling downwards is as inevitable as traveling from Tuesday to Wednesday, because spacetime is warped such that
"downwards" and "next Tuesday" are in fact pointing the same direction. By contrast on Earth, there is only a slight downward bias in the direction of "next Tuesday," with time still pointing mostly timewards and not very downwards, so you can compensate for the tendency of your position five seconds from now to be downhill by putting a floor in the way.
So it is entirely reasonable to expect one technology for intensely distorting space (and possibly imposing some kind of time stasis) around the contents of a capsule to be on some level conceptually related to the physics that allows one to warp space and time in other ways.
This might explain why Dr. Briefs, the great capsule researcher, is even able to
recognize the gravity generators of an FTL starship. And why decades later, he and his daughter are able to build their own starship so quickly given the saiyan pods as working example models. And why two decades after
that, his daughter is able to build a freaking time machine under "in a cave with a box of scraps" conditions.
The great majority of the Briefs' marvelous inventions are in some way related to gravity, space, or time. And it is reasonable to associate them as inventors with this 'schtick' in the same sense that Edison is associated with electricity... even though Edison had many inventions, including some famous ones, that didn't use electricity in any way.
