I don't think there's many vegans eating it. I can't imagine why they'd want to, except possibly on the very rare occasions when they're at something like a cookout, the host has bought vegan burgers specifically to cook for them, and there's not really anything else there that they can eat... Although it's kind of hard to imagine there's not going to be anything there that they could eat, because you know there's going to be buns, condiments, burger toppings - nothing wrong with having lettuce, pickles, mustard and ketchup on a bun and calling it a day.

I think it's mostly aimed at those who feel guilty about eating meat - whether guilt about the fact that an animal had to die to provide that meat, or because they don't really believe meat is healthy. And there are plenty of people who eat meat because they like it, they feel good on it, and it tastes good, but constantly feel horribly guilty about eating meat because they believe the constant narrative about how bad it is for you with all that fat & cholesterol, and that it truly is terrible for the environment.

But they only feel guilty about it -they don't want to become vegan, but they'd be willing to give it a try if there was something that tasted just as good as meat. That's where the vegan burgers come in, helping satisfy the meat cravings of someone who doesn't really want to be vegan, but feels so guilty about eating meat that they'll give it up anyway. They're the ones who will probably go for lab grown meat too.