Don't think it works like that on btcjam does it?
no. btjam only need your ID and other information. that's why the risk are huge.
https://bitcointalk.org/index.php?board=65.0 <- it works like that here.
[1] 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. [2] 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.
you sure it's lending and not borrowing? if it's the later then the answer is they don't want to sell their collateral because of various reasons. for example they won't sell their Full Member account for 0.1
BTC because they know they can get more on the long run. also if the lender got "persuaded" and ended up getting burned it's their fault.