It sounds good, but isnt it too risky? As i understood, this system is under no ones control, even the law cant help lenders, if borrower refuse to pay

Thats why interest rates are higher, in order to maximise lender's profits. Risk/profit ratio must be interesting to investors
That's all very well, but is there any way to mitigate the risks? It will be awesome, if there are any!
Yep, I know one of such ways. There is a professional scoring procedure of borrowers, before their loan requests get published, its like a reputation in the «lending world». This system allows lenders to choose a reliable borrower, therefore reduce their risks.
Also, there is one more way! Lender could get part of his investments from a compensation fund, that was created by a system.