Sure, some can’t be bothered. Yes, some would rather pay a professional who often (notably, not always) would do a better job. True, some things you fully grasp only after years of experience. Still, it’s not that difficult. You don’t need to know how to write an OS or build an ICE from scratch to do an adequate job. People routinely learn to do quite complicated things out of passion and/or necessity even when it’s far disconnected from their primary profession; spend some time with the right sources of information and you’ll be alright.
If you're capable of buying a VPS you're capable of sticking a USB cable and an Ethernet cable into something.
With VPS, you typically must know how to SSH and be able to find your way around the system entirely without a GUI (which could be jarring at first). Personally, when starting out, I was always anxious about messing something up so that it makes the server impossible to boot remotely.
Pi, meanwhile, is just another computer you physically have and can do all the normal things you do with a computer you physically have with. It has some hardware peculiarities, but then it’s also simpler to set up than building your own desktop (which, by the way, is another thing non-engineers routinely do).
Right, but you are comparing your setup and its costs to wordpress.com, which is not self-hosted and does not require that understanding.