Actually it really isn't.
The more expensive something is the higher the ongoing costs to maintain it. It's the same case with cars where more expensive ones are also more costly to maintain and fix.
When people buy a more luxury item, it's because there is something about the item that they value where no cheaper equivalent exists. MacBooks certainly have several such features: quality of display, ecosystem integration, form factor, battery life, speakers, aesthetics... These things might not be the same things you value, but for those who care it's just as important. This is also why some people buy luxury cars and others just get the cheapest whatever that gets them from A to B.
FWIW, I run an HP Ryzen laptop that cost me just $350. But I do so because the 2h battery, non-HDR (and probably not even 100% sRGB) 1080p screen, lackluster speaker, and "borderline serviceable" trackpad don't bother me at all. I would not buy a MacBook as it offers no features I care about at a significantly higher price, but I respect people who do buy MacBooks because they fit their needs.