I don't have anything against cryo, so this are tentative suggestions.

Maybe going in for cryo means admitting how much death hurts, so there's a big ugh field.

Alternatively, some people are trudging through life, and they don't want it to go on indefinitely.

Or there are people they want to get away from.

However, none of this fits with "I'll write you out of my will". This sounds to me like seeing cryo as a personal betrayal, but I can't figure out what the underlying premises might be. Unless it's that being in the will implies that the recipient will also leave money to descendants, and if you aren't going to die, then you won't.