Well, the sum of "things like travel and industrial output" (which are affected by individual actions) is enormous. Human emissions in total are, shockingly, the sum of all emissions caused by individuals. What I'm really getting at here is that we need to see something like a Gini coefficient, distribution breakdown, etc. of emissions across the entire population (globally would be informative, within more developed countries would also be informative). You look at people driving around megayachts and taking private jets everywhere, obviously as an individual their impact is a thousand times out of whack, but I'd be surprised if that amounts to more than a drop in the bucket unless you start expanding that category as wide as to include "car owners" and such.
I bring it up because it seems like the kind of "I can't do anything as an individual" line of reasoning I see so much seems to be really problematic and preventing these problems from actually being resolved.