A gas station sells gas that is gone within weeks. But someone fills their car, and drives to Mountain View and gets a job that changes your life.
Helping a business grow by 10% more each year because they were an early adopter to websites is something you impacted, even if your code isn’t there to remind people why.
“All we are is dust in the wind.” (Kansas and Ecclesiastes)
The world isn’t a static place. The impact is often closer to saving X thousands of people a few seconds than anything more meaningful. Perhaps the indirect result is someone finds the love of their life but it could just as easily be a life changing STD or getting run over and impacting many people means many such indirect changes both positive and negative.
Very odd to look at it and know that I'm probably one of 2 or 3 people who know why that specific code is there, and also to know that the base of this is still running.
But that's the exception, not the rule.
To quote Roy Batty, "All those moments will be lost in time, like tears in rain."
If there's anything I've noticed in this industry, it's that abstractions tend to outlive their origins. For instance, back in the 80s the Unix systems my workplace used (and subsequently, many of the applications they ran) had an 8 character max username length, and although those old Unix boxes (and their vendors) are long gone, we're still given 8 character usernames since nobody wants to find out the hard way that there still are some applications that depend on an 8 character max or which truncate longer usernames to 8 characters.
If you want to make a lasting impact on an industry but you weren't able to get in on the ground floor, your best bet is to get into advanced R&D, whether at a major hardware company or in academia. Anywhere else and your knowledge will either be wasted because nobody cares or it will be siloed off because the company will never open-source the tech you pioneered (and someone else will likely take the credit for it later on when they create an open-source equivalent).
Every couple years since, I've gotten a bug in my butt and investigated how many sites still had pieces I'd clearly worked on. On this most recent occasion, I could no longer find anything. They've changed over to some open source CMS and I was unable to find anything I had built.
It's been 12 years in there since I left, but as far as I can see on the front side everything I'd written is gone. It's a strange feeling, like 5 years of my life just evaporated.