Tiredness in office work is caused by boredom, worry, or resentment. Basically it is a huge "do not like" feeling. Source: Dale Carnegie
About right, though I don't think "boredom" is really it. I can and have done entirely mechanical work for something I wanted to accomplish for hours on end without boredom.
The tiredness, and the dissatisfaction, are almost entirely psychosocial, between lack of intrinsic investment in the work itself, and the various social indignities associated with modern corporations.
David Rock has a good book, Your Brain at Work, which details a number of specific psychosocial factors in play at work.
Doing something boring means you have more abilities than required, so pretty sure you will be never fired for underachievement.
I don't know about your work situation, but in my experience in the US, incompetence gets almost no one fired in the modern corporation. You get fired when there are reorgs, and the Top Men cut head count. Sometimes the Boss is given a say in who is dumped, and sometimes not. He'll dump the guys he doesn't like, who don't show loyalty, faster than the guys who don't produce. If you're bored and dissatisfied in your job, it's very likely the guy your boss doesn't like is you. Particularly if you're given to pointing out faults in plans, instead of spouting happy talk.
Job cuts from the Top Men have little to do with you at all, while when the Boss is given a say, it's more about social factors than productivity. Taking a job beneath your general capabilities is no protection against cuts from the Top Men, and may be a net negative protection if the job leaves you dissatisfied, and therefore less pleasant to the Boss.
I've seen a lot of your posts. You can string sentences and ideas together. Guys who can do that don't grow on trees. If you find a job challenging, while you have the basic background knowledge for it and find the diligence to apply yourself to it, the job is probably hard, and the Boss won't easily find someone who can do it much better. You have to judge your competence, but I recommend you judge it relative to the competition, not relative to your own standards.
The point of my Ranger story is that what was soul crushing for me, was a day at the amusement park for him, entirely on account of our different attitudes toward the work. Having spent some time unemployed, I catch myself whenever I start thinking I "have to go to work". No, I "get to go to work". Yay!
And there are even better and more satisfying jobs I could work at. Yay!
they would think you should have sticked to the boring, comfy, well paying one that you can do without many challenges and seek excitement elsewhere.
If it is indeed comfortable, secure, and well paying, that's not bad advice. If on honest evaluation, it really is a good situation, maybe what you need an attitude adjustment more than you need a new job.
Dale Carnegie's "do not like" feeling is largely a "do not want" feeling. From this and other posts, I see a lot of "should" and "duty" in you. Embedded in every should, every duty, is an implicit, unexamined, "don't want to".
How about you lay aside that duty for a second, and honestly evaluate based on the available options, and what you want? Beyond duty, do you want to support your family? Of your available options, which ones are the best for all the things you want?
Often times, we're doing out of a leaden sense duty what we would want to do if we allowed ourselves to examine our options based on what we want.
My point is this. You leave the comfortable boring job and start looking for a new one (or start looking while working). Pretty sure it requires a knowledge you don't have, because jobs that require learning nothing new are probably precisely the boring ones. First issue is not being hired at all, because the HR idiots want 3 years o experience in a technology 5 years old and we want people who can hit he ground running yada yada. But let's say they are willing to invest. Still there is a probation period - usually 3 months here - where they can still easi...
Here is an interesting blog post about a guy who did a resume experiment between two positions which he argues are by experience identical, but occupy different "social status" positions in tech: A software engineer and a data manager.
The author concludes that positions that are labeled as code-monkey-like are low status, while positions that are labeled as managerial are high status. Even if they are "essentially" doing the same sort of work.
Not sure about this methodology, but it's food for thought.