I used to be in the "individual choices don't really matter" camp but my thinking has changed in recent.. months?
Individual decisions matter but so do top down decisions. In order for collective bargaining to work, the people on the bottom have to make demands and the people on the top have to give in to demands. Neither one works without the other. Governments cutting meat subsidies won't magically make people eat less meat (unless you believe in efficient markets). People eating less meat won't magically shift government spending subsidies towards sustainable crops or meat replacements.
Both has to happen at the same time.
Okay, now that that's settled, there's the problem of lobbying and the status quo. When industries are threatened, particularly wealthy ones, they will try to protect their interests by buying off politicians. There is a similar lifestyle status quo preservation mechanic for the public. Some people just refuse to change their habits. See: coal towns in the Appalachia
Regardless of whether you think the blame lies with the consumers or the blame lies with government/corporations, or even if you think it's a mix of the two, we will have to fight against capital's self-preservation instincts sooner or later. For me, at least, it's easier to talk someone into eating less beef than it is to talk lobbyists out of Congress. The final boss, in my view, is, and always will be, global capital.
Also the implication climate change has for politics is: no more "moderation". No more "you can pollute a little if you promise to keep your total emissions low". No more trying to take it slow and easy. We literally do not have the time for incrementalist policy-making, which has done fuck all in the last 50 years except, in the best case, if I'm being very charitable here, slow down runaway climate change but is ultimately neither able to stop it nor reverse it.