As a softeare dev who used to work in the contracting space, I cannot tell you how many stories I have of licensed, insured, regulated tradesmen going to jobsites and the outcome being burned down houses, flooded houses, oil spills, trees falling onto houses, and just monetary and physical damages galore.
If you have the time and desire to do things carefully, truly, then you will do things carefully. You'll find that tradesmen have plenty of expertise and money-- the only thing they don't have is time, and it really shows.
This is not the metric. It's a self selected post hoc measurement, subject to mental bias.
The proper way is to measure all pros that do a task, then the ratio that did badly, then do the same thing for amateurs, and do so carefully (preferably somehow double blind) to remove cognitive bias. Then compare ratios.
When such things are done, I find almost every time notice my (and likely your) anecdotal claims vanish. I suspect this is such a case.
A good example is a friend owns a business that handles two cases of building things: doing it themselves first time, and fixing screwups done by amateurs. Literally (I've seen the books because I was surprised when he told me this) 75% of their revenue is repairing things people screwed up by not hiring pros, and then it costs much more. (It's related to wetland construction issues).
Then don't construct in a wetland? 90% of building involves avoiding risk, not developing Herculean skills to overcome risks.
It would be like if I lived in Thailand and then complained that I got electrocuted trying to set up a really complicated AC system. If you aren't willing to put in the time to do that kind of electrical work safely, then ask yourself why you really want to live in an area where that type of work is a pressing requirement.
I don't subscribe to your philosophy that all contractors are superheroes that are immune to messing things up. I'm not paying $125 an hour for a guy who lives in a tin shack to come and tell me how much of a pro he is just to disappear the moment I discover some deficiency in his work.
Failure through believing your skills are above what they are is not unique to wetland.
>I don't subscribe to your philosophy that all contractors are superheroes
I've never stated anything close to that. Since you've moved on to strawmen, there's no sense discussing further, since you apparently left this discussion some time back.
If you have the time and desire to do things carefully, truly, then you will do things carefully. You'll find that tradesmen have plenty of expertise and money-- the only thing they don't have is time, and it really shows.