Still, I'm selfish enough that if I had cancer I would treat it, which is what was actually being considered/compared to cryonics.

I often do the selfish thing when I don't have enough willpower to do the right thing, but it doesn't take a whole lot of willpower to not sign up for cryonics. Based on the fact that someone coined the word "cryocrastination", I'm betting it takes quite a bit of willpower to sign up.