You are missing an important step.

What you have described actually has no effect other than putting yourself at risk of accidental margin call.

Borrowing bitUSD by itself is a neutral position. Because you owe the same bitUSD you just borrowed. If you borrow 100 bUSD no matter what BTS price does, you will still owe exactly 100 bUSD. In closing this position you will simply get back the BTS you had to lock up to borrow. Nothing will have changed in your balance except you needlessly paid a couple transaction fees.

If you want to leverage your BTS you must first borrow bitUSD and then purchase more BTS (or something else) with that borrowed bUSD. And then hope whatever you just bought with the borrowed money goes up in value. I do not recommend anyone doing this that is not fully aware of the risks and how it works. This is a great way to lose all your money.