It's not required by MRA rules, but *highly* recommended by everyone. Even if someone does a fundraiser for your broken ass, it will barely make a dent in the bills a solid crash can create. Someone mentioned the helo ride from HPR - if medics perceive any kind of imminent life threat, you are being flown. Without insurance you're already several thousand in the hole before you even get to the ER door. Even without a life threat, something as simple as a broken arm or collarbone can run into several thousand dollars, particularly with followup care. Also bear in mind an ER is only required to treat you initially - followups can be denied on financial grounds if they know you can't pay. I know the OP indicated they wouldn't race without insurance, but I'm pointing out the ramifications for others that may venture here.

Racing without health coverage isn't just irresponsible, it's one of the most outright stupid things you can do in this sport.