I am in my mid 50's, a 2 time "late bloomer" , so have been a physician for 20 years, EM boarded for 12. I have been 2/3 full-time, 90 hours per month, for 4 years now. Over these 4 years I've made some efforts to break out to something different with no success. I went from a salary of $400k at high acuity, high volume ED to $250k currently. The money is fine, we live comfortably, though not extravagantly, and I carry a mortgage on an expensive hose and have put one kid though college out of pocket at a UC school out of state tuition. I wouldn't be as comfortably situated now though if I hadn't socked away money when I was making more in a LCOL area.
Incidentally, I quit my $400k job when I started getting some burnout and the first stages of employer craps on doctors emerged. I tried out a CMG, full time for $240k and it was horrible, quit in less than a year.
In my first few months I did that, before pandemic, I thought it was the answer for a living for 8-10 years until full retirement but between my advancing age and the repeated toilet swirlies our specialty is subjected to, I've had enough and I quit. I work my last two night shifts ever later this week. After that I will work prn a couple shifts per month but hope to be out of EM entirely by the end of the year, if not the summer. I have a line on non EM clinical work and hopefully business development work but will keep mum, sorry, until its a sure thing.
OP, you are wise to lay groundwork for an exit early. I am at the point where I'm convinced the job is shortening my lifespan and there is probably a number where I would continue at my current schedule but it's not one anyone now would be willing to pay. I considered MBA but did not want to make that kind of financial outlay and I think anyone past age 40 would not likely get a good enough return on that investment if self-funding. The Pharma/med tech industry is tough to break into in our specialty, but if you start early, I would think that holds promise. Medical monitor jobs via CRO (contract research orgs) abound, don't pay all that well, but are a way to get a foot in the door. Some Pharma companies have fellowships geared toward turning early career doctors onto the Big Pharma lifestyle. Medically oriented financial/VC jobs are pretty much impossible for grunt level guys/gals, with a lot of competition for that work amongst the C-suite types.
If I was younger and a more traditional pathway, I would focus on getting my med school debt paid off (I did HPSP scholarship) then make liberal use of FIRE calculators to find a number where the retirement nest can grow from and then as quickly as possible get to part time work, cutting out night shifts as quickly as possible.