Being a famous sports figure in general makes it easier to invest in these assets. Many VCs will bend over backwards to have a famous sports personality involved in their firm or investments.
Even a non-famous person with ~$20mm to invest (somewhere around the after-tax amount of his rookie contract) would not get a seat at the table at these VC firms.
Yeah, it seems like these "investments" are halfway to endorsement deals. He endorses the companies for marketing purposes and is paid in access to investments that typically aren't available to someone of his specific tier of wealth.
I also see no real indication that Barkley is especially good at what he is doing here. Is there a reason to believe that anything but luck separates his investments, including in crypto, from deals his peers like Tom Brady and Steph Curry made with FTX that got those guys pulled into the company's legal problems?