The money they would be paying back they could use to build up their business.
I doubt anyone would do this investment for a return.
1. Loans once repaid can be lent out repeatedly, thereby helping many more people.
2. Repaying a loan at a reasonable interest rate puts lender and entrepreneur on a more equal footing, and is therefore more dignified for both.
3. Loans encourage a proactive and independent mentality on the part of the entrepreneur, rewarding success rather than neediness.