Anyone can be an investor, rich or not doesn't mean much, agreed the rich have better opportunity to invest in any company they chose to invest on because of their huge capital, but there are opportunities for none rich people too, all you need is know the right place to invest on.
Rich or not means a lot
It even rhymes!The rich can invest more without fear which means they don't suffer such a big loss, they aren't scared and can sleep well, they buy a larger piece so they make more money when it goes up.
It's much harder to become poor when you're rich than rich when you're poor.
You're right that we all can invest but don't say that it doesn't matter how much money we have because it does.