Not sure what your point about existing categories is, but with respect to the point that it might be all roses for the US to invite foreigners to found companies, just off the top of my head:
Most of the investors that get involved are likely to be in the US, they may have limited legal avenues to pursue if the company fails due to negligence or fraud and the founder moves back home.
Depending on the financial status of the founder, the US might have to choose between providing social support or paying for deportation.
I'm not saying it's all roses. I'm talking about risk/reward.
I'm trying to compare it to the potential upside of any immigrant category. Entrepreneurs present some downside, but no more than any other visa/immigrant category. One heck of a lot more upside though, IMO.
Most of the investors that get involved are likely to be in the US, they may have limited legal avenues to pursue if the company fails due to negligence or fraud and the founder moves back home.
Depending on the financial status of the founder, the US might have to choose between providing social support or paying for deportation.