I think you leave the failed character dead and look elsewhere for a generic megalomaniac.
See, the thing about Superia, is how, like a lot of the other villains from Gru's Captain America run, she represented things that were happening in America in the 1980s-1990s, like how the Serpent Society were a trade union, but for (snake-themed) supervillains, who were able to keep their members from having to deal with the prison-shaped consequences of their actions, or Flag-Smasher and ULTIMATUM were anti-nationalists, intent on forcing a one-world-nation, while the Power Broker and Karl Malus represented the steroids scandals that rocked sports and pro-wrestling, Super-Patriot/US Agent wanted to be a new hero for the Reagan-era America, the Scourge was a mysterious and deadly killer causing deaths mostly amongst an underground subculture of men leading secret double-lives, clearly echoing the AIDS panic, the Resistants were the metaphor for angry militant minority groups, Nefarius was the clearly insane person allowed to roam the streets unchecked, the War On Drugs gave us The Slug, getting fat/round/lardy off the profits of his trade, and the Armadillo represented the humanoid-animal threat that brought the nation to it's knees in '82.
And Superia? For all her claims otherwise, she's not a feminist, she doesn't want equality, she's a man-hater claiming to be a feminist, to the point that she actually wants to purge the world of men/guys/dudes and create the future Thundra comes from. And hey, we're on The Internets. Even 20 years on, misandry disguising itself as feminism isn't exactly hard to find online. Thus, the "problem" only comes from taking her stated ethos at face value, rather than seeing her for what she really is. I guess what was missing was to have her face a heroine who actually is what she claims to be, who can call her out on it, and unfortunately the closest the Avengers franchise really has to offer is the fat Ms Marvel?
As for "why would Superia change her ways?" I'm going with "repeatedly losing to men made her seriously re-evaluate her life-choices, goals and methods." That, or "working for HAMMER gave her the opportunity to do Evil Science Stuff legitimately and get paid for it, rather than having to do so underground.