Imagine everyone living for 250 years. Personally I'm not willing to sacrifice an extra 150 years of life just to kill a few billionaires.

Society would not collapse. Anti-aging could actually save us from an upcoming demographic crash. As populations urbanize, birth rates go down, and most advanced nations are way below replacement rates.

Meanwhile, between cheap solar, probably fusion (see my other reply), and cultured food production, our per-capita impact on the planet could well shrink by a lot over the next fifty years.