Do you really want to use your $4 in futures trading? In my knowledge, it seems like you can also trade on Bing X even with a small amount of money for this kind of thing.
It's okay with futures as long as you have knowledge of trading.

In futures, you can grow it if the position you choose is always right and the analysis you do is correct, but if it's wrong, you will be liquidated quickly unless the leverage you use is low.
But for small amounts like that, usually high leverage is used there.