Yes, that's what I meant by how much money you bring into the company.
If you bring in $1B a day (and save countless lives) and I can easily hire another employee just like you, why wouldn't I have done so already? Perhaps that is your point?
Be that as it may, how overpaid do you think tech employees are compared to the cost of replacing them?
Year over year wage increases relative to all workers and competition for labor in the tech sector are the signals you want to use. Total mergers and acquisitions and number of discontinued software products would be good secondary signals.