You have to remember that you don't actually have to have 60% of people quit meat cold turkey to reach that number, you just have to get ~6/10 meals averaged over everyone meals that would have had meat to not be either by switching to something naturally meatless or using a subsitute. You can drastically reduce meat consumption across a population without anyone being vegetarian or vegan.

> ideological motivation

Maybe it's possible you don't literally mean "ideology" but the reasons people choose to consume less meat are typically epistemic:

* Because it reduces their carbon footprint and is better for the environment.

* Because, for them, cutting out meat improves their health. Usually related to cholesterol, blood pressure, heart disease, fiber, and sometimes osteoporosis.

* Because veggies and meat substitutes take longer to spoil.

* Because veggies and grains are less expensive.

* Because cutting out meat is associated with long term successful weight loss.

The only ideological reason to switch is animal suffering.