I have an honour's degree in the conservation of biology & a Post Graduate Diploma in the science of psychology.
Refrain from replying to my posts with strawman arguments (e.g., stating l meant something that l did not write in the post or a reply). If you want to understand more about me, then read my many posts, rather than simply assuming something
@NegativeInf @Showroom7561 @climate
The scale of an individuals effect, depends on how many other people do "it".
As one example, if l was say "No thanks! I've brought my own non-plastic bag" to the retailer asking if l want a (plastic) bag, that action didn't stop that plastic bag from being manufactured.
But, if 90% of people stopped using the retailers plastic bags, that retailer would order less plastic bags.
Scale this up on a population level (& do the math).