In my experience, there's very little correlation between salary and longevity. There definitely seems to be a correlation between salary and "demand."
For instance, Kubernetes is really hot right now, and there's a limited supply of people who know it, so people that know it can make upwards of $200K.
OTOH, you could be the world's greatest Windows admin and you'll be lucky to make half that, because there's a million people who know Windows.
TLDR: specialization is more lucrative than sheer hard work and expertise.
Yes, although you always need to be looking toward the future. The market for Y2K consultants, even "world class" ones, wasn't so good in 2002. (Admittedly for a variety of reasons in addition to the obvious one.)
For instance, Kubernetes is really hot right now, and there's a limited supply of people who know it, so people that know it can make upwards of $200K.
OTOH, you could be the world's greatest Windows admin and you'll be lucky to make half that, because there's a million people who know Windows.
TLDR: specialization is more lucrative than sheer hard work and expertise.