You become time-constrained by the very virtue of living. As a 40+ noob, you're worth much less for an employer than a 22-25 noob. You have about the same experience, but younger noobs have more energy, less health problems, much less expectations, much lower costs of living. Also, at 40, you're supposed to be halfway through your expected career; deviating from a standard life looks weird, and from what I can tell, most entry-level jobs don't like weird.

Such is the job market.

Well, some doors are closed forever.

With 32, I'm too old to become a police officer in most states in my country, for instance.

I didn't say they close because of writing software. They close because of living your life.