I'd be very curious to hear from other highly paid/desirable careers like doctors and lawyers (and even "real" engineers) about how their hiring pipeline works - is this unique to software developers?
https://www.baltimoresun.com/1997/03/01/ama-seeks-limit-on-r...
For lawyers, theres no such constraint and the limiting factor is typically attending law school and successfully getting a job as an attorney. The demand for attorneys is driven mostly by the business world and thus the economy. After the global financial crisis, there was a severe contraction in the demand for lawyers and many had to leave the industry. There are many ex-lawyers and law school-trained professionals who chosen other careers.
Also the pace of change in law and medicine is extremely slow. It's an exciting year when you have to consider a new drug or new law.
Otherwise, the only question is whether you can increase volume without doing any career-ending malpractice, and how you round off the sharp edges of your workplace.
edit: this is for seniors. Associate lawyers have very high attrition rates, losing 1 in 5 per year (1 in 4 for people of color). The vast majority of people leaving law school will not be doing law after 6 years.