someone shouldn't spend a small fortune on a speculative immortality procedure

A very small fortune, since I had already mentioned it would be paid for with life insurance.

the fact that it's not their life

Did a double-take here. Sorry, I phrased it poorly; we were discussing cryonics in general, with focus on practicality for everyone in the conversation; not just me.

cryonics is just freezing a corpse to most of us

... are your opinions on cryonics by any chance mostly a result of popcultural osmosis? Please don't be offended, just a shot in the dark.

"life would be boring after (Average Life Expectancy in my Country) years, because sour grapes"

About right, although it was fairly vague.

"life in a society where you have no useful skills, are completely ignorant and unsocialized, and everyone you know is dead would be distinctly unpleasant"

... no. Do people seriously try this? It sounds vaguely familiar, but I've never really encountered it... There was a brief "what if everything sucks?" "why would they bring you back if everything sucks?"; that's about as close as anyone got. (Neither of those voices is me.)

"Seriously, life is pain bro"

I'm not entirely sure what you're trying to convey with this - are we talking antinatalist-style arguments.

The first is either a clever attempt to get you out of a perceived scam or a rationalization

???

None of them seem like they've given up on life.

One assumes that it's somewhat difficult to debate cryonics with people who have committed suicide, which is what you seem to mean by "given up on life".

They've certainly given up on getting more ...