Systems can be broken and incentivise poor behaviour while individual actions also make a difference.
Besides, where will your political change come from? people who wont even change their diet? Just like how all those environmental protections were brought into being by people who criticised the people chaining themselves to trees for thinking individual actions mattered?
The meat industry is terrified of vegans, they spend millions rewriting laws and producing propaganda to limit us. maybe they have reasons why.
Ok I’ll humour you: what are vegans wrong about?
Land usage?
water usage?
Fertiliser usage?
That animal farms are hubs of disease outbreaks?
Thermodynamics?
Where the Amazon is going?
That killing/branding/doing surgery/forced impregnation etc when you don’t have to is wrong?