Earlier quoted context omitted.
The higher you go, the more expensive you get. And the fewer places see the value you bring compared to a cheaper "senior sw dev" with 5 years of experience. If you want to be paid more than someone with 5 years, you have to generate more value than they do, and you have to persuade the hiring manager that you can generate more value. The fraction of places that can see that is smaller than the fraction that can see…
The mere statement that a 5 year ‘Senior’ software engineer has more perceived value than a ‘Senior’ software engineer with 20 years of experience is just crazy. Let’s replace ‘software engineer’ with ‘electrician’ and then tell me this is sane.
A 5 year software engineer may have more perceived value per cost than a 20 year software engineer. Sure, if they have the same salary, you hire the 20 year engineer, but they don't. The 20 year engineer expects more pay, and (rightly) won't work for 5-years-of-experience wages. So you have to find an employer that perceives the additional value of the additional 15 years of experience.