What they do with those 50 million later is somewhat immaterial, that's sort of what I'm pointing out. If they make money with the 50 million, sure, they'll have to pay some taxes, and the difference between the loan and their money is that they get to pocket the money in the latter case, vs using it to repay the loan. If they lose money, they can either opt to use the loss as a deduction, or close down the LLC and file chapter 11. If they used their own capital, then they lost the money out of their pocket as well.
That doesn't really have much to do with what's cheaper for that person in order to get those $50 mill to begin with.