It is better to buy some bitcoin then earn interest.
It is good but there's no passive there. You need to do it again and again. You need also to be patient for waiting for the price increase if you want to get the interest (profit) and for the price decrease for buying it again after selling. Though this is assured income if you are good on doing this type of activity repetitively.
old your bitcoin will not grow into more. if you want to grow and make a profit you can make trades by selling and buying bitcoin. but it will not provide a steady income