For example, a few years back there was a Ponzi scheme in the US called PermaPave which took money from a bunch of small investors on the pretext it was being invested in environmentally-friendly stone paving slabs. They didn't make a single cent in profit from the slabs - all the payments out came from other investors' payments in. When the whole thing imploded none of the small investors could afford to do anything about it. Unfortunately for PermaPave, they'd also taken a much larger investment from a company actually interested in buying stuff from them, and when they breached their contract that company had the money to investigate them, figure out that it was a Ponzi, and sue everyone involved.

Another problem is that companies don't want to deal with a load of small investors if they can raise money from a few rich investors instead: it's a lot more work and expense for them, the small investors don't have the same kinds of connections and expertise that the big VCs have, etc. The main reason to raise money from ordinary people is because you're a scammer and big investors have the expertise to spot you, the resources to investigate you, and the money to sue you if they do invest. (The less money you invest, the less you can rationally justify spending on due diligence.)

Ordinary people are at a fundamental disadvantage to the rich here no matter whether they're legally allowed to invest or not.