How could Bitcoin lending be secured? I have been thinking a lot about platforms that allow us to borrow/make money. 
Such a platform would be really wonderful, mainly for people in countries such as Brazil, which has high taxes on interest.

The problem is the risk. 

I read in the news about a guy that did not pay the amount he was supposed to on btcjam, which was really bad.

Leading to the question: How will we be able to have a more stable and reliable Bitcoin lending service, so that people might trust bitcoins even more?
There is currently no mechanism known to enforce loan repayments, as the lending happens on the blockchain and the repayment is tied to an offchain contract.

The revenue of Bitcoins is very high, because the risk of the borrower evading repayment is very high.