People always forget that Double Fine kickstarted a Documentary about game development. The main pitch was to see everything behind the scenes about game dev that you never hear about otherwise. They didn't even have an idea for what the game was really going to be when they started, just that it would be an old school adventure. They explicitly said it may fail horribly or be a shitty game, but at least you'll be able to see how it happened.
So sure, "$400k" might have been enough to fund the documentary and some game, but when they piled on all that extra money of course they were going to find ways to use it.
Once that went gangbusters and everyone realized that you could kickstart the actual GAME instead of this crazy hedging-on-a-documentary pitch DF had to start with, it opened the floodgates for all the games being kickstarted now.
Double Fine is doing exactly what they promised.