I think the point is not that the individual should abandon efforts to modify their own habits. The point is that we should also be focusing just as much if not more energy on efforts to regulate and/or change industries that are responsible for more emissions by orders of magnitude. Some small but significant subset of the population going vegan, buying electric cars, or biking to work isn't going to offset the biggest offenders.

The biggest offenders are fighting tooth and nail to be as profitable as possible at literally any cost. You can be damn sure that if what they produce becomes less desirable in one industry, they will try their hardest to get picked up in some other industry. They'll have scientists finding some way to be useful somewhere and demonstrating it with research and lobbyists that will then get the government to mandate/subsidize it so that they make as much money as possible.

I've personally tried to "vote with my wallet" but industries have found ways to green-wash their products to give the impression that choosing their products would be the responsible choice when in reality it is not. Ensuring that your spending only goes to companies making an honest effort to do all they can to be carbon neutral or environmentally friendly is more than a full time job at this point. The only way is to ensure that governing bodies dictate the behavior of these organizations and even individuals so that it is no longer up to the organization/individual to "do the right thing".

Without proactive, strong government intervention we will be well, well, well beyond the point of no return by the time "voting with our wallets" and "modifying our behaviors" changes industries and society enough to have a significant impact.