Your post negated in two words:

Value relativity.

You're deciding what you value. That's not necessarily what other people value.

You assert that life is disappointing. I don't find mine so. Nor are any others of those whose lives you personally find disappointing obliged to find their lives disappointing, either. They can find meaning and value where they choose.

I'll take what I can get; I find value in it. If the thought of an ending is so bitter that one cannot countenance beginning, however, no amount of longevity will ever impart meaning, for even an eternal life is merely a sequence of things which begin and end in turn.