What exactly are the consequences of breaking an Early Decision agreement?

I promise I’m just morbidly curious! I applied to colleges three years ago and have thousands of posts about it! O:-)

Breaking the agreement can and should have severe consequences for someone whose intention was to game the system. What I don’t understand is whether those consequences extend to someone who honestly underestimated the aid they would get. People say that it’s more permissible to break the contract because the financial aid isn’t enough, but the student is the one who determines if the financial aid is enough. So what stops the system-gamers from giving that excuse and avoiding consequences?