Big companies usually work either by C-level exec fiat or by middle management promotion plans. Neither of which usually want small fish. If you work for a $100 billion company and you say: I need $25 million to pursue an idea that might make the company 2x or 3x, there's a good chance they'll say: no, sorry. We prefer to invest that $25 million to either improve our $5 billion product or invest in an idea that could become another $5 billion product.

And from this we get the innovator's dilemma :)