When someone takes a loan latter can take another loan by few minutes where all discussion will be in pm then will make public posts and then took a loan. In this case, 2 people will be looser.
I'm not sure I'm following this. Are you saying that unsecured loans are risky? That's shocking but still not a good excuse for account trading, not to mention all the other potential shenanigans. For example when you take an account as collateral you could be getting a hacked one, which the perp is basically selling to you with no intent to pay back the loan. Essentially you're creating a market for such accounts.
If you want to give out unsecured or poorly secured loans - take the risk yourself, don't push it on the community.