> If your work improves the productivity of 100+ other people, you're surely worth the price.
> If your work saves $500k+ in annual costs, you're surely worth the price.
This is only half of the story, though.
The real question is whether or not the company can accomplish the same thing at similar quality in a similar timeframe by hiring someone with a lower compensation request.
The value you produce for a company sets the ceiling for your compensation, but not the floor. The floor is set by market rate compensation that other developers are asking for the same job. Developers also tend to forget that the features they code and ship require input from a lot of other people along the way: Managers to manage it, QA to test it, security team to review it, devops to help monitor it, designers to design it, and so on. If you look at a single feature, estimate the revenue, and then assign 100% of that upside to your own work then an experienced hiring manager is just going to roll their eyes at the hubris.
What you really need is an ability to show that you, specifically, have a track record of accomplishing these things better, faster, and with less headaches than the other people applying for the job. A track record of professionalism, upward movement through notable companies, and references helps greatly.
The key isn’t just to show that you can do these things. It’s to show that the company will benefit significantly by hiring you, at a premium, relative to hiring any one of the tens or hundreds of average developers they can find who will do similar work for less. The ideal highly paid candidate is one who can show a track record of self-managing and big picture thinking as much as possible. If I’m paying someone a premium salary, I expect they will require less hands-on management time and will streamline their interactions with the rest of the team, saving us both time and money. Find a way to show that in the interview.