I think what motivates people is their health and how they feel.
Trouble with guilt is it makes veganism sound elitist. “Killing animals you should be ashamed or your polluting the environment etc is all fine and good but it hardly moves mountains.
What motivated me was lower cholesterol. Building up ones bone mass. Gaining muscles with plant based protein. Avoiding cancer and heart disease. Better energy level. Losing weight.
Right now there seems to be an uptick in colon problems in young adults even in their 20s. What better reason to give up meat and processed foods. .?