This is exactly right about negotiation and your skillset. I have seen performance engineers in the right place at the right time get 10-20% of their benefit to the company (I have seen both $1 million/year compensation for line workers and $10+ million/year for very senior folks).

Very highly skilled engineers in specific niches can basically price themselves like monopolists, because the company can easily figure out how much money they are leaving on the table by not hiring them. This is not like "feature work" engineers, whose value is very nebulous and unknown.