Sure, but Guardians was a risk, and so is Ant-Man. Trusting the future of the entire brand on the C-list replacements who don't have nearly the iconic qualities of Captain America, Thor, Iron Man, etc.
You call those risks? When it comes to Captain Marvel, every MCU film that has come out so far are mere hills compared to the Mount Everest of risks that her film is burdened with. There's a reason it took 20 films for Marvel to finally make a movie that is unquestionably about a female character.
If Ant-Man fails? Meh, we've got plenty of other characters to try out. If Captain Marvel fails? Well, I guess female characters don't work as leads so cancel everything we've got planned for the other ones. Cripes, we don't even have to wait for Captain Marvel to fail. If DC's Wonder Woman, which comes out before Captain Marvel fails, you can bet your hard earned dollars that Marvel Studios will get cold feat when it comes time to release their female lead super hero.