And if you did get it approved, and managed to sell the treatment to everyone in the USA who has Crohn's disease, you'd need to make a profit of several hundred dollars/person just to pay for the cost of FDA approval. Realistically you'd want to charge more to recover up front risks, the cost of marketing, and uncertainty about what fraction of the target population you'd successfully sell to.
So no, not really in the range of crowdfunding.
And if you did get it approved, and managed to sell the treatment to everyone in the USA who has Crohn's disease, you'd need to make a profit of several hundred dollars/person just to pay for the cost of FDA approval. Realistically you'd want to charge more to recover up front risks, the cost of marketing, and uncertainty about what fraction of the target population you'd successfully sell to.