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
Although holding alone won't increase your bitcoin, for as long as the value increases, you are able to make income from it. It might not be a stable one, but just consider it as passive income. And while you are just letting some of your bitcoin earn passive income for you, do other things that can give you more bitcoins actively. By opening a small business that accepts bitcoin as payment, you might strike gold if you just work hard on it.