I think that professional boxing could also be considered an extreme sport. I'm aware that I'm a bit late with my answer, but I couldn't stop myself from tossing in my 2 cents.
It takes a lot of training and dedication to get into the ring and fight against another skilled opponent. And as you said, one punch can definitely change your life. As for me, I'm also getting into boxing and building a home gym. I recently discovered a heavy bag for apartment living, and I can't wait to add it to my setup. Anyway, thanks for starting this discussion, and good luck with your training!