Why would BP change if you don’t?
Because BP isn't a human being it is a legal entity without inherent value other than those that we as a society allow it to have. If society decides BP should stop existing that's just a logistical effort (replacing energy needs, finding jobs for the workers there etc etc) where as if society decides I should stop existing that's a crime against humanity. Putting legal entities and humans on the same level here is a false premise in my eyes.
Also: Arguing for removing BP from the world IS showing a willingness to change personally because it means changing a lot of other stuff too that will affect everyones live.
And I think it’s important to change yourself as well, so you can demand it from others.
I'd argue that that only works on small scales. For big changes we need to agree beforehand that we want and will do the change and then do that change together. Demanding someone jump first won't work here.
I'm not sure I see the difference between bringing big oil down versus bringing animal based food down. Both are critical pillars of our current societies, changing that takes a lot of work (even if we were to convince everyone that that change needs to be done). My personal decisions don't really matter as long as everyone else keeps going the way they are.
That being said I basically have a vegan diet and I very rarely use transportation that runs directly on oil. I just don't think that gives my arguments for societal changes any more weight. These arguments are right in my opinion, independent of whether I already live the change or just argue that the proposed changes would be beneficial.q