Building savings contract or "normal" credit?

Quite simple. You borrow €300,000 without having any equity, build your house, and after a year it has to be forcibly auctioned off for whatever reason. However, the house and land only cost €250,000 to build because the rest were incidental costs. So the bank will hardly get that amount. By then, perhaps only €5,000 has been paid off. That means the bank still gets €295,000 from you. But it won't be able to sell it for that much and maybe gets €260,000 at best. Then you still owe the bank €35,000. Do you still think it was a good idea to start out without equity? ;)