How dangerous is this sport really?

So here is my issue, my boyfriend (we are very committed to each other) wants to start racing and he has a passion for it similar to my passion for cheerleading. However, I really don't want him to race because I've only heard about how dangerous, risky, and life threatening this sport can be. But I also don't want him to feel like I'm controlling his life because that's not what I'm trying to do. Im trying to understand what he is thinking and what the risks actually are. I'm afraid that if he does race then I may lose him forever but I'm also worried that if he doesn't race then he will have some sort of regret and hate towards me. I've tried to talk to him about how I feel about it and he always brings up cheerleading and how it's dangerous yet he still let me do it and he still supported me. And why can't I support him. But I don't see how cheerleading would be similar to motocross on a danger scale. From the little bit I know about motorcross I feel as though it is much more dangerous then cheerleading even though cheerleading is dangerous itself. And I also don't know if it's just because I do cheer that I think it's not as dangerous. I just really feel like I need some other opinions. So if someone, anyone could help me get a better understanding on the sport or advice on what I should do I would greatly appreciate it.