He could upload it on bitfinex and use the free MarginBot to lend the USD out to traders. He would receive around 20% a year. At least it was that way some months ago.
The risk would be that bitfinex is an exchange and exchanges can go down.
Investments are always risky. You should think of them the way that you might get 100% in a year on top of your investment but when you start you lose 100% and the question is open if you will get your investment back at all.
That is a tremendous return rate, is this still occurring? I don't generally trust exchanges with my coins but with a return like that and knowing that finex has so far proven reliable, I might give it a go.
I'm not aware of any investment offering that. Though be happy about it. All of these ventures ended in scam, inept businessmans or other problems. Everyone invested did lose more than they won.
is this the margin funding feature of bitfinex you are talking about?
i did a little search and read about it, i think it is not a fixed interest rate but a changing rate that you can set as an offer which can be lower.
can anybody explain with some numbers how much is the potential of earning this way
Yes, it is not fixed. It is a normal market where you offer the loan for the price you want and others take it.
That is why I suggested marginbot. Free on the forum. It creates the offers automatically and makes sure that your money does not lie around useless and is getting the best rates.
I used it some time and it brings in returns. I think I calculated it to 24% a year. Or even higher? Anyway, I'm not sure if the reward dropped in the last months but you might try it and find out for yourself.