Earlier quoted context omitted.
That's defeatist. Small changes are not the only things that matter but saying "everything or nothing" is not helpful. The collective change that's needed to effect change begins with individual steps, like not taking a private plane when commercial will do.
I can’t think of a single case in human history where indiduals acting alone made a real difference in widespread issues like climate change. So suggesting it starts with individual steps seems wildly inaccurate.
And your actions do have an effect: by providing an example to others, making it more likely they too will participate; and economic, by reducing the income generated from the activity.