Obviously your mileage may vary, but I think you’ve got the curve backwards here. There are far far fewer late-30s roles for men, as on screen most look too old to be “young” and not old enough to read as “dad” or “distinguished”. If you look very very young or older you may be able to jump the gap some - I like to use nick offerman as a random cherrypicked example, he was 38 when he starred in Parks and Rec, but reads as mid-40s or older on screen.
Then on top of that, many of the people who have stopped acting by their mid-30s are either the people who were not very good or couldn’t handle the ambiguity/uncertainty. The population of actors who remain and are still working in their mid-30s, by and large, are very good and very committed. Not only are they very good, they know many/most of the other good actors who go up for the same roles as them. They have an established network, they have a reputation, they have an inside track on a lot of opportunities.
Random anecdote 1: a mid-30s friend of mine could guess what 5 or 10 people would be auditioning with him for basically any commercial in NYC after reading the script. He just knew who the casting directors would be calling alongside him, and the other actors knew too. It’s a small world once you make it to a certain level.
I think an imperfect analogy would be that it’s like graduating from a software boot camp and trying to go right for engineering leadership jobs at Facebook or Google, or maybe a better example is graduating law school and immediately trying to oversee an major tech acquisition. For sure, there are some that probably could, but even if they have the technical skills, there’s the network, the relationships, the hands on experience that makes it very unlikely.
Fun anecdote 2: acquaintance of mine, successful character actor (like “hey I recognize that guy from something” successful not “John c Reilly” successful), worked steadily from his mid-20s through his mid-30s and then his acting income dropped by 90%-ish over the next 8-10 years. He got a little older, greyer, more distinguished, stayed in great shape, and when he hit 45-ish the work started flowing again. He’s not making the same money as he did, but it’s back to a regular stream of income.
I think if your goal is to go to acting school and semi retire, working in tech part-time to make money, and try moonlighting casually in community theater and the like - that’s totally doable. I think if you’re going to try to join the varsity teams, it’s going to be really tough.