Running and basketball I had to quit because of impact on my body overall, though not so much my head. Wakeboarding I quit b/c of a torn ACL and minor concussions in my 20s. Skateboarding is obvious lol. Surfing doesn't have very much impact, but in big waves there is a whole other set of risks.
Anyway, I was just a bit surprised by your comment b/c out of all the sports I've done, BJJ seemed like the one I could do for a very long time just by sticking with people I know and trust.