It is true that some people, as they get older, claim to find games less interesting. In my opinion, some of them simply jaded a bit, and would be a good thing for them if they tried to find enjoyment again in the small things. I know, because I was there too. It depends a lot on the culture.
There are also others that start claiming games are useless, immature and that the world will end if youngsters keep playing them.
Entertainment has been useful even before civilization existed, and those that enjoy the time to entertain themselves, do; even if it is in the form of working on dream projects. Yes, that is playing too.
As for your other point, there are objectively very few (if any) topics as interesting as games for CS people, given the so many areas of CS (and non-CS) they encompass at the same time. Hardly any other area of work touches so many domains. Only operating systems, browsers and CAD apps (and maybe Emacs ;) are close as vast.
There are also people who still find enjoyment in small things, just not in games. It's not like computer games are that enticing beyond a certain point.
You can wonder around shooting aliens or casting spells, or exploring space colonies, in some commercial game that's basically the nth clone of 1000 others before it so many times before it loses interest...
It's like watching superhero movies for life. Yeah, people do it. But people also learn to appreciate more mature movie plots than "kid finds out they are unique, has responsibility to save world" or "millionaire with faults devotes time to fight supervillains", as their life experiences (e.g. kids, divorce, health scares, job trouble, mortality, love affairs, betrayal, etc) are not exactly the same as their brooding misunderstood teenager years when they wished they would "show everybody" anymore...
The same way there are more "mature" movie plots than those that you are (kind of) mocking, there are also more mature books than children stories, more varied music than pop summer songs and, indeed, more games than your "nth clone of shooting aliens".
By the way, I have had a nice daughter and health scares like anybody else, and no, that has nothing to do with maturity or with games becoming boring. There are many game genres and of course you like different ones when you are 15 vs. when you are 50. I literally thought like you in my early 30s, when I had literally zero free time and kept thinking "yeah I am past that, leave it to the young generation, I am responsible now".
Not like those immature infants that play games. Got it!
What is interesting is subjective, and I am not going to seriously tell anyone what is interesting or not. But there are certainly areas in CS with just as much or more breadth and depth than game development. As someone who works in AI now, I would say it covers even more areas of CS, and requires more math.
There is also computer security, which can be as high level as web app security, or as abstract as the number theory powering cryptography.
I love game development, and games, but it is a bit disingenuous to hold game development up as being the ultimate discipline in CS. It is certainly not.
Anyway, neither AI nor security cover that much of CS (they are parts of CS, and there are many others). Games, however, heavily use both of them (and many other parts of CS).
The AI you use in games is very rudimentary and smaller in scope compared to AI used for applications in the real world.
A lot of the recent outcry over games industry being horrible is a bit exaggerated. I'm glad some of these issues are getting attention, but it's far from being like that everywhere.
It's really compelling work.
Maybe you've been in a situation that hasn't been like that of others but you are not an entire industry of people. Confirmation bias and small sample size are things to watch out for.
I feel like the exploitative nature and below-industry living-working standards are what pushes people away from the field in the first place.
The video gaming industry makes in the same order of magnitude in revenue as the global movie market. It certainly isn't a small industry.
But that is not reason to quit game development entirely. It is still a good hobby that makes you a much better programmer, because it touches so many areas of CS and math. 3d graphics, state machines, trees/graphs, pathfinding, multithreading, memory management, vector math, networking etc.