This sentiment is not unique to biomedicine. It's pretty often you see people finger elitism or capitalism for screwing people over because "I can make it myself."

Ethically, you are more than welcome to experiment on yourself. That's your prerogative. But, as has already been expressed here, the issue is once you start giving your creation to others. Even when the science is conceptually very simple, like in the case of nucleic acid vaccines, a huge number of variables can impact the safety and efficacy endpoints for the recipient. That's why trials and regulation are essential.

Are these regulatory systems perfect? Absolutely not (they are in dire need of reform). But they form an essential safety barrier for the general public. Decrying them as class warfare is incredibly naive.