I think you don't understand the meaning of a collateral, you are not paying 120% in crypto, it is the guarantee, you can't say "pay".
What you pay is the interests, 5% interest monthly, saying "60%" out of nowhere doesn't mean anything.
I'll give you an example, with big and round numbers so it is easy to understand:
1 BTC = 10000 USDT
You want a
10 BTC loan for
15 days, 5% monthly
0.167% daily, you have USDT as collateral, so you need to send me:
--->
120000 USDT = 10 * 10000 USDT * 120%
At the end of the 15 days, you will have to give back the capital (10 BTC) and you will have to
pay the interest:
--->
0.2505 BTC = 15 * 0.167% * 10 BTC
Then I give you back the collateral 120000 USDT.
So the percent paid on the loan amount is:
--->
2.505% = 0.2505 10
Hope it is clear enough

Sure I do understand what collateral is, Jees

I mean if I had 120K USDT, I'd buy 10 btc, keeping my 20k untouched or using it for other purposes why should I pay any interest to anybody? To remain safe against btc price drops? What about the (more probable) price surges?
Secondly, in banking we don't use daily, weekly, monthly interest rates, it is so confusing, conveniently we use yearly interest rate indexes to have a common terminology such that when a greedy shark says I pay you 5% interest loans we could compare his offer with what a regulated bank offers instead of banging our head over and over against the wall when we discover he means 60% interest per year.