Fact checking out of boredom: of the big movies in 2011, thor and captain america are two of the more expensive entries. The only one abnormally higher is because they had to pay an overinflated salary to the star. Planet of the Apes, Fast Five, and…the hangover 2 (
) cost less than thor. Despite the insistence disney-marvel is an underdog working with scraps, budget was about that same as x-men first class.
Seriously, these things were almost all more expensive than any other comparable films, the stuff that got bigger budgets were Nolan's Batman (revival of a previous blockbuster franchise, Begins budget is still in line with the MCU first films), the Spider-Man trilogy and two films with troubled long productions (Superman Returns and X-Men: Last Stand) and Marvel kept upping the budget on each one. Marvel immediately pushed the Iron Man sequels budgets over what Nolan got for his sequels. They act like it was like X-Men and X2 where Fox came in with below average budgets (with X2 getting a later bump) and got blockbusters out of them. Marvel bet on all of these like Sony did with Spider-Man. They were not snuck out and wow, a hit, let's make more towards Avengers!
Warner certainly came along five years later and tried to spend their own MCU into existence by dropping insane amounts of money on the Academy Award winning Zack Snyder (and CGI for Henry Cavill's upper lip) but they've written this status backwards into the lore like Marvel wasn't outspending everyone but Sony from the start. And
none of this includes whatever they spent on marketing, the comics, merchandise, video games, etc.