I'd be in favor of this technology if, and only if, we've also figured out a way to deal with the overpopulation problem.

Being young at 50 works for the Star Trek timeline, because you can go live on any planet or starbase you want to, and not have to worry about money.

On Earth, wouldn't typical countries start to become like India? And if India is already the way it is, wouldn't it devolve into a complete hellscape?

Yes, it sounds selfish of me to say I would be against life-saving technology, because it works too well. But if the alternative is letting much of the world become as overpopulated as India already is, then that's not a price we can afford to pay, even to save millions of lives.