I would argue being vegan is a very hard change, equivalent in my mind to asking people who care about the environment to never fly or get in a car with an internal combustion engine. Those people exist, but man is that a lot to ask!
It is a much smaller ask to opt into paying 5 cents more for a burger to offset. But with travel the connection to emissions is more obvious and wealthy people have a larger share (a rich person doesn't eat 10x more steak than average, but does fly 10x more).
You lost me on the comparison between never flying/driving and eating responsibly and well, but i think the "never" part of the equation is going to cause a lot of friction.
If being a vegan is hard, use condiments! Don't be a vegan, just eat way less meat (especially red) and stuff made with palm oil which would both benefit both the climate and your health. Actually the heck with the planet, heart disease will take your number faster than climate change.
"By 2020, 90% of Ford’s North American sales will consist of larger vehicles with lower fuel economy" Not buying an SUV that never leaves the pavement which rides on GIANT tires might also be something to consider in the personal choices category. If you really need to see above everyone else, install a periscope.
And yet still only 2% of the population is vegan.
I don't suppose it will work if we just leave this to the people who care. Most people do care, but enough to sacrifice their comfort.