There's a difference between misery and limiting ones intake of climate-unsustainable calories. Not eating meat a few days of the week seems a small price to pay for allowing more people to live.
And walk me through how we limit population to allow resource excess, without artificial population controls and managing the economic impacts of a shrinking population, and I'll consider it.
Would you rather live in a world of 100 billion on efficient food only or 1 billion that can actually eat meat and other tasty things?