You were experimenting with sports betting and found yourself profitable with your strategy. However, you can’t raise a bigger bankroll to generate larger profits. Then there’s this one guy who believes in you and is willing to lend you money, of course, with interest, almost like a loan shark rate. The question is, would you see this as an opportunity or just a trap?
It's a trap, you will be a prisoner of that debt... In this case, you will do all the work & bear all the risk while someone sits back and makes money off of you. If you are profitable, just continue doing what you do and slowly raise your bankroll & stakes. If you are really good, it will happen sooner than you expect.
Maybe I could understand someone in a desperate situation making a move like this... For example, someone close to you is ill, and you are really good at sports betting, so let's try to get a big buck quickly. Even though that is very tricky, I would understand.
So, if you are not in a hurry and no one is chasing you, just take it slow & easy...