Don't you get it that poor people don't have the money and the safety net to risk investing, remember that you have to have a bank account to invest and a mobile device at the least to manage, the poor are too busy finding means to make money and investing is far off their mind to even consider. It is easy to say that investing is for everyone because a lot of people here are privileged and think that what they can do can be done by other people so yes, investing is for the rich and those with the privilege to make more means to make money.
I was a poor person, I am still a poor person, I will probably never be rich. However that is not an excuse to not have any money in crypto neither, I have grown from 17$ in investment 5 years ago into having 3.5 thousand dollars today, it took me 5 years to get there, I could have been much richer if I didn't sold my coins here and there, I made very bad investment choices.
I sold some to spend on vacations and other stuff because it was the first time in my life that I had some money so I wanted to do what rich people do, go to nice hotels in a different nation type of vacations, that alone could have been 5k+ today if I kept my bitcoins (much cheaper normally, but bitcoin went up a lot). So long story short if you are poor, if you start with $17, you could still grow to a lot of amount, won't make you rich, but you could at least have a decent amount for you, 3.5k thousand is a good amount for me, it is about 5 months of salary for me, that is a good thing to have.