Also it is just a nice feeling, every time you use something you've repaired. I'm not very handy, but every time I open the door that doesn't squeak anymore it cheers me up a little.
I feel it's my personality, but as soon as I fix anything I am overcome with anxiety every time I'm near it for fear the issue will return or that my repair was faulty and inevitably prone to cause further damage.
I don't know why I get this way. In spite of all my worries I've yet to truly fuck up an appliance I've repaired (furnace, microwave, dish washer, workout equipment, countless car repairs, electrical, plumbing, carpentry...the works).
As far as I've ever bothered to explore the feeling, I think I have an inherent trust that products are manufactured with care and attention while my repairs are often ad-hoc suitable replacements with salvaged parts, or even just duct tape and glue. Experience should tell me that things are often built to minimal passing standards so this idea that a manufacturing line that spits out dozens(?)/hundreds(?) of these products in a day are any better than my attempts. Lack of documentation is often a big one. If my repair seems to make more sense why wasn't it done like this before? Am I missing something that should be considered? What caused it to break that I haven't addressed? etc.
If it were socially normal and expected to try and repair things, and you did happen to blunder, that would be a normal blunder that everybody makes. But if you go against the grain and try to fix things yourself when it's becoming less and less expected to do that, that could make a mistake feel worse.
Of course one might quite naturally just feel more responsible for a possible mistake when doing things oneself hands-on rather than when delegating things to someone else in any case. Not saying you should, but it'd be quite natural to.
If it broke and I replaced it with a broken appliance then the manufacturer/distributor is to blame. If it broke, and I broke it worse (made it unrepairable) then it's my fault. Sure, I was trying to be frugal and save money doing it myself, but having to admit fault to a professional could be embarrassing.
Easier to displace blame instead of facing truths I guess? Despite repairing this much stuff, I still consider myself a pretty bad mechanic, maybe I'm just too hard on myself.