[amrcnimgrnt]

Reversing the flow of aging is reversing entropy locally, so you're, overall, increasing entropy more outside of your body.

The live forever types are just assuming that energy will be plentiful enough to sustain hundreds of billions of people indefinitely [1] and heat easy to dissipate

[1] The population of the earth is stable at 7 billion only because people have this nasty habit of dying. If we stopped doing that, the population would grow exponentially at the birth rate of 1.7%. Or a doubling every 42 years. In 160 years (not that far off from the current record of longevity) the world's population would hit 100 billion people.

Of course the "live forever" types never mention that eternity is a promise for the privileged, and not for the masses.