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?
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.
Doctors and lawyers are in no way comparable and don't switch jobs as developers do.
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.
