There is a real taboo about mentioning veganism. That said, it's fairly mainstream these days -- any big enough BBQ will have to have some option. Lactose/gluten/shellfish/peanut etc issues (that aren't choices) are a fact of life, and any crowd will have at least one vegetarian/vegan that can benefit from some of the overlap.
It's not about convincing people to change their behavior directly though. People hate being told what to do. It's also hard to guilt someone into change. Some of the changes are just no-brainers though. Plenty of people try veganism and give it up. How many people try an EV then give it up? (I don't actually know, but it doesn't seem like many. They're so fun to drive.) More upfront cost, yes, and that may be the reason not to get one, but it pays for itself over time. Same with an induction stove. Who actually likes being in a superheated kitchen on a summer day? Who likes how much harder it is to clean a gas stove? The risk of burning yourself or starting a fire? Worst case: some of your pots don't work and you have to replace them.
You don't have to mention this stuff out of the blue, but if someone is thinking of redoing their kitchen? That's the time. Buying a new car? That's the time. Someone has money to invest? Get some solar panels instead.
It's not about convincing people to change their behavior directly though. People hate being told what to do. It's also hard to guilt someone into change. Some of the changes are just no-brainers though. Plenty of people try veganism and give it up. How many people try an EV then give it up? (I don't actually know, but it doesn't seem like many. They're so fun to drive.) More upfront cost, yes, and that may be the reason not to get one, but it pays for itself over time. Same with an induction stove. Who actually likes being in a superheated kitchen on a summer day? Who likes how much harder it is to clean a gas stove? The risk of burning yourself or starting a fire? Worst case: some of your pots don't work and you have to replace them.
You don't have to mention this stuff out of the blue, but if someone is thinking of redoing their kitchen? That's the time. Buying a new car? That's the time. Someone has money to invest? Get some solar panels instead.