Yes correct, if BTC falls you;re on the hook for adding more collateral, but there are several options.
Let's say you added 1 BTC and you got $25 000 on a LTV of 50%
If BTC keeps dropping lets say to $25 000 each
- Add more BTC to keep the value at 50% collateral so you'll need to add another 1 BTC
- You can also pay back a portion of the loan faster and reduce the payments
- Or you can extend the loan on a higher collateral level and pay a higher interest rate
So there are options so you can avoid margin calls and losing your BTC, but yeah its not without risk and you need to have done your homework