At an abstract level there's some appeal to this notion.
At a practical level not so much, though, and that's even before you get into the nitty-gritty mechanics (like tax law here lol).
The adverse selection risk is huge, unless you go for very young people. What this means is that for people who're already "established" and/or have a track record:
- if they have a worthwhile idea they won't have trouble getting better, cheaper funding than this
- ergo if they're asking you for this kind of funding:
-- they either blew through their previous earnings and don't have a concrete idea to pursue next (NOT GOOD!)
-- or they aren't actually that "established" / lack a track record, and therefore are actually exactly the kind of people you don't want to invest in like this
...so pretty much investing in people proven-successful won't be happening.
We can roll back and consider younger people -- those too young to have any great success to there name yet -- and now there's some possibility here: catching brilliant people on the way up and giving them a further hand up.
Your problem here is that:
- you're competing with student loans as a choice of funding; for a student to pick your investment over a student loan it has to be a better offer. For any student that anticipates serious success you'll have a hard time being a better offer in terms of net payout; student loans are painful b/c their payback is frontloaded into the postgraduation years, which are at the point of the lowest lifetime earnings potential...but in net amount 3% of lifetime earnings will be much greater than the total amount of student loan payments.
- most of the really talented individuals won't even need your money, as there's an unbelievable wealth of grants and scholarships and fellowships for the truly exceptional in all walks of life (science, music, athletics, etc.) that they pretty much don't need funding until after they graduate. After graduation they might take you up on the offer but as time passes they become ever-more-likely to be able to raise cheaper funding for whatever they desire
...so even going after the young'ins leaves you unlikely to be attracting the people you'd want to invest in.
Which means good luck: even if you had the money together if you extend the offer at a price that'll leave you likely to turn a profit it's unlikely to be compelling to anyone you'd want to invest in.
And if that doesn't dissuade you think about the tax law implications: given how easy it would be to do an end-run around inheritance + gift-tax law with this type of "investment" -- and that that this end-run route isn't being taken 24/7, etc. -- I can guarantee you the recipient of this "investment" is going to be taxed on it as income (or at even worse rates, perhaps)...which means the math for the recipient is even worse:
- your investee now has to decide if, say, 125k or so (about what'll be left out of a 250k investment after taxes) is worth 3% a year
...which further contributes to the adverse selection issue as you're only really offering half as much as you think you are.