The Spartan terror training was mostly about making the Spartan youth desensitised to regularly purging the Helot caste to make sure they didn't get any ideas above their station; not creating supermen. Never forget that the Spartans got absolutely crushed by the Thebans at Leuktra despite outnumbering them nearly two to one because the Thebans just deployed their formation in an unorthodox way through extreme concentration of force; including an elite band of gay lovers; all on one flank to implode half the Spartan line of battle ASAP and then rout the entire army. Thebes crushed Sparta so badly that Sparta never really recovered as a military power after that point.
There is I think some debate about that in the modern research since I have seen a few suggestions that the original helots weren't necessarily treated that badly (nor really tended to rise up in revolt) and the "helots" as we we understand them today only really coming into existence and becoming a problem in their conquered territories once they expanded beyond their original base in Lakonia.