I think you also make the mistake of believing that craftsmen always do professional and above all perfect work. My neighbors had their interior doors installed... many crooked. The neighbor opposite wanted a special Italian plaster technique, the professional said "Of course we can do that"... in the end, he knocked it down again and did it himself because the "professional" simply couldn't do it and also didn't come for a correction.
Tiles... our tiler immediately handed us a sheet showing how much overhang is allowed... and fully used that allowance. Well, I'm not picky, I want to live in it, it's not a tile exhibition... but it is far from perfect.
The bricklayers messed up a rough construction measurement for the door. I only noticed it when I wanted to install the frame. Then I spent an hour rasping Ytong...
My buddy is a kitchen builder, he smeared two nice new white walls and the joint between two panels doesn't fit 100%...
The civil engineers set my cistern a bit too high...
The plumber didn't lay the insulation on the roof properly again, drywall boards had to be replaced due to mold...
When you do something for yourself, you put in more effort. But you should stop after 8 hours, after 6 during strenuous work. Because, indeed, the professional has the advantage that he can still go on after 10 hours... I lose a lot of strength after 6 hours and then start making mistakes because I no longer work with control.
But admittedly... I also enjoy it. I like working with the miter saw, cordless screwdriver, and hammer once in a while as a change from working on the computer.