I never wrote that I was "confident" about it.

I fly paragliders for fun, but that doesn't compare at all in excitement to starting an engine where I just changed the timing belt.

I watched more than a few hours of video to do that. But it was possible to do with the help of YT videos and VW's official workshop manuals that you can buy and download from their erWin website.

I started from absolutely zero.

I've replaced the timing belt, water pump, alternator, brake fluid, master brake cylinder, removed and cleaned the air throttle body, flushed the coolant system, replaced the radiator, replaced the shocks, replaced the exhaust, removed the turbo and replaced the waste gate, used OBDS CAN software to troubleshoot sensor issues, etc.

It was a gradual process over several years. It was a lot easier since most of it was on my second car that I could just leave in its garage while I got parts or tools or watched another 10 hours of YT videos. But some of the stuff was on the curb.

If you're a software engineer and get paid by the hour, it's absolutely not worth your time if you just look at the money.

But it can be a fun hobby, and I really like knowing how the car works when it's starting to make weird noises on long distance vacation trips. Just know that it's not that hard in theory, but in practice the wrong bolt will shear off just as you have to put things back together and drive off with the car. So always have a plan B, especially if it's your daily driver and you can't just leave it for a week or two.

Having said all that, if you're interested in cars, then this video course is excellent. I paid for it a couple of years ago, and don't regret it.

So, reading my original comment and you response again, I can see how my comment came across as "it's easy to replace the timing belt, just watch a few YT videos". I agree that that's definitely not the case.

It does require more than a few hours, but certainly starting with a few hours of video to understand the basics of automotive engineering is incredibly useful when you want to learn to fix cars. I taught myself years ago starting with a basic Time-Life book and worked my way up to factory technical manuals and research papers. I learned the theory first from books and then the practical later by getting my hands dirty and eventually being mentored by others who knew what they were doing. What I discovered from this path is that many of the mechanics out there have never really learned the first part, and while they're good at repairing what they know, they get stumped when they actually have to diagnose something new because they do not understand the underlying theory.

Everyone's first time with each of those subjects is prefaced by "a few hours of video" (or equivalent).

Nobody goes from doing nothing to doing everything in one go. It's the sum of many iterations of education then experience on many smaller subjects.