The other option is to run for office and effect change that way. That one just might do something.
If you want to reduce the consumption of some thing, make it more expensive.
Paradoxically: increased efficiency reduces costs and so increases total consumption. This was noted by economist and engineer William Stanley Jevons, in the 19th century.
There are different ways of increasing costs, and not all necessarily involve prices (or taxes), though those tend to be the most effective and easiest ways to do so. Legal, social, and moral costs can also be imposed (criminalising use, making use anathema, making use taboo), but these take time to impose and have various side effects.
This is a difficult problem, and even recognising the dynamic is difficult. It's deviled ecolologists, economists, politicians, and others, for over two hundred years (and arguably, for over two thousand).
If increased capabilities allow more parties to engage in an activity, you'll increase total consumption.
If increased costs reduce the effective maximum scale of operations, you'll tend to have reduced consumption.
One formulation I've come up with is that "bad hygiene leads to decentralisation", where hygiene is meant in the general sense of systemic health and efficiency. Anything that reduces the capability of scaling up operations will lead to more and smaller rather than fewer and larger units of operation. This is something that proponents of decentralised systems might want to consider.
https://mastodon.cloud/@dredmorbius/36518392
https://www.reddit.com/r/dredmorbius/comments/7h8sqk/open_th...
I don't think this is true. Humans are deeply social and copy each other. One can easily see this with young humans, but I didn't fully appreciate this with adult humans before I saw it myself. When I turned semi-custom-vegan, I did hear that it is kind of pointless because animals will still be slaughtered for others. But even suprising to me it turned out that several of the people I interact with started to reduce their meat consumption as well. We aren't all egoistical ignorants that only think of their immediate benefit.
But that example is extreme. There's strength in numbers, even smaller ones. If 5% did what you describe, there'd be that much more people demanding streets that are safe for biking, etc.
If you make the world better by being less bad, then chances are you are already doing what one human can do. That is fine and enough for one human, by definition.
When we aim for the stars we first must learn to walk, and be content with little steps for a very long time.