There's no actual ban on poor people investing in SEC-registered securities. What is at issue is an exemption to the usual SEC disclosure requirements, which is

There's no actual ban on poor people investing in SEC-registered securities. What is at issue is an exemption to the usual SEC disclosure requirements, which is available in limited circumstances. In cases where a company's investors consist solely of a small number of "accredited investors", Congress enacted an exemption to the usual SEC disclosure rules, on the assumption that such groups of investors have the resources to conduct their own independent investigation of the offering. A company can choose not to use that exemption, and instead do things the official, open way: issue securities to the general public accompanied by the required disclosures. That allows the company to take investment from anyone, while also protecting the public by ensuring that that the offering is above-board and accompanied by enough information for the public to make an informed investment decision.