You should borrow bitcoins when you have a valid reason and do some research of what kind of loan you are going to use and especially the interest. To be honest it's too risky to borrow or even lend bitcoins here, it's just too risky
Indeed when you need it and you got a good reason to do it it would be worth it but if this is only for the cash I would simply not do it at all because it will than be not worth it.
Yes if you are doing it for the reason that you just need money it would not be worth it and even be stupid to do.
If you have an idea that can be profitable and you need to lend money, I would say go for it!
If you borrow money for the sake of investments and you saw that you would possibly make profits on it then you should not hesitate to borrow money as long you know that you could able to repay it soon but for those things that are useless and you just want to borrow then its a really bad idea because you would have a hard to to repay it back.