I'm curious because I don't know how this works exactly, how much collateral do you have to put up to borrow something on a decentralized exchange? If it's less

I'm curious because I don't know how this works exactly, how much collateral do you have to put up to borrow something on a decentralized exchange? If it's less than 100%, how is it enforced that I ever return the money, and if it's more, why would I borrow if I already have the money I need? Asking in good faith. Also if you plan to buy a house, a bank can give you a mortgage over let's say 25 years where information about your identity, income and credit history is used as a risk assessment, and the loan is backed by the whole existing legal system where your home can be repossessed if you fall behind on payments. You can get a LTV ratio of even 95% in some cases. How would this work in a decentralized way ever? On the other hand, if you already have, let's say 500k in the bank to buy the house outright, why would you involve cryptocurrency in the transaction. The counterparty is going to probably want to receive their money dollars in a bank somewhere, are you sure that a bank is not going to ask any questions when you do your magic conversions to dollars from crypto and try to send someone 500k? This doesn't integrate into the real world well unless the other person selling wants to receive crypto already and is ready to take upon all the risks themselves that transferring, accepting and holding cryptocurrency entails. At that point you don't need to do the conversion magic anyway.