It's hard to change unilaterally. For instance, it's easy to say "stop driving everywhere", but the majority of locales do not cater well to non-drivers. It's easy to say "stop flying", but in practice that's almost equivalent to "don't travel any significant distance from home, ever".
People aren't stupid just because they don't drop everything and make one specific goal their highest priority above all else. Many people haven't even thought about that goal, and even for those who have, it may not even objectively be the highest priority goal.
People could for example elect governments that want to build transit or dis-incentivize carbon heavy activities and incentivize their replacements, but they don't.
We're actually quite lucky to have a decent Green Party and a proportional government system here (NZ), where the Green Party can get up to ~15% of the vote. I wish it was more though.
In a world where no party is proposing reforms that will actually do enough, I feel like I basically have a responsibility to vote for the most environmentally conscious not-totally-insane option.
Indeeed. In the UK, no party has an environmental platform worth mentioning. There isn't even an environment position in the cabinet any more - just industry.
Conservatives promise to dig up the country.
Lib dead promise to dig up the country, slowly.
Labour promise to dig up the country, for the people.
And the greens promise not to dig up the country, but will make us all live in grass huts.
People aren't stupid just because they don't drop everything and make one specific goal their highest priority above all else. Many people haven't even thought about that goal, and even for those who have, it may not even objectively be the highest priority goal.