Borrowing money always costs money be careful with this. It's never really useful to borrow it only if you are starting up something and need some capital.
Even then the smartest thing is not to borrow cause if you start up fails then where do you find the money which you borrowed + interest. Think about all this before you start borrowing or lending money out.
You are right but if you need money fast and there is no other way it can be smart if you can also pay it back later.
You should only do it when you can do this...