Your honest account seems more like a series of errors you've invited on yourself. Your motherboard prices are insane. And this litany of spontaneously breaking components make you sound like you're just yeeting the stuff around. Maybe that's all unfair, but it's how it comes across.
Now you're comparing the prices of the i9-10900 to the 5900X, when the 5800X's performance more than matches it. The 5800X is about 10% cheaper than the 10900 here.
If you don't understand the platform and chipsets, use a picker service or even buy a bundle. There are lots of component sellers flogging matched components in tested configurations. You won't get top-spec motherboards but there's no reason to spunk €300 on a desktop motherboard.