Loaning people your money is a good way to lose it all quickly and all for what? A tiny piece of interest? Most people will likely just take out loans to pay them back until they build up enough confidence to take a big chunk and run off with it.
not if you have a policy of "never lending someone big amount of bitcoin without a valid collateral". you can sell the collateral if they default, and limiting the loan with no collateral to 20% of their account's worth will reduce your risk.
Well the ones who scam will try avoid using colleteral. It gets to a point where the person will build up enough previous trades that they try persuade the lender that it'll be ok without any because they've had no problems so far. The borrower might get greedy by the proposed interest and lets his guard down. It's really pointless taking out loans to me for any other reason really so I'd be suspicious of anyone who does so especially when they have the same amount in collateral. Why would you bother lending money if you already have it? Doesn't make sense.