There is a rule: while making investments in cryptocurrency, spend only that amount that you aren't afraid to lose. And if you are a poor person, then that amount will be lower than that of a rich person. But you can buy as little as $10 in the spot and $1 in the future, but if you are a newbie and want to make an investment, then the future should not be your choice.

The amount does not depend on the status of being poor or rich; it depends on the capital you have to invest, and the capital should be the one that your life won't be affected by in a way that you should not be fully dependent on it.

The minimum time for holding purposes should be around 2 years, but in present, I think 1 year will be enough because the bull run is yet to start after the halving event, BTC can make a new ATH after the halving event, and the price of BTC will start to increase, so holding BTC for more than 2 years does not mean you can make a profit in 1 year.