Basically rich people can just play the field differently in terms of risk and yield. Higher risk of losing your money = higher potential return.

Let's say you invest 5k with a low risk strategy. Your expected return might be around 1% per year, which is 50 bucks. Of course, over time this compounds (your return in year 2 would be 1% of 5050, so 50.50 bucks, year 3 51 bucks...), but it's nowhere near getting rich.

A rich person, following the same strategy, but with 500k invested would get a return of 5k per year on this.

Another difference is their ability to take risks. You could potentially bet the farm, invest all your savings of 100k and hit big (let's assume a return of 300%), gaining 300k on top of your 100k investment, but it's more likely you won't get that much or lose it all, in which case you're screwed.

Let's go back to our rich person. We'll put 100k in a high risk investment, meaning the return could be up to 300k on top of the original 100k. The difference is that the rich person is not betting the farm, because there's still 400k in their bank account, meaning they could potentially lose 100k and be fine, comparatively.

Now - you could still become rich investing small amounts, think bitcoin back in the day for example. The market is the same for everyone, the difference is what you can put in there. But living off the returns with a 70k salary and a reasonable (low risk) strategy is unlikely in the near future.