Again, it does not take days to put together a PC. It should take a few hours AT MOST including the OS install/drivers. I have been putting together PCs for 15+ years, it is not some engineering feat that takes massive labor or time.
Plus after you put it together, you are done. You are not going to disassemble/reassemble the PC every month. At most you will be upgrading single parts at a time which depending on where it is will take a certain amount of minutes.
Yes, this is true, not days but certainly not 30 minutes for the average person as there's far too many variables involved.
I've been building PCs since 2004, so I know how these things go on average. It's the same thing I see people say for why they buy food outside instead of just cooking. I've been putting off fixing my airflow on my PC as my idle temps are quite high but that can be due to the ambient temperature in my room.
Technically it's not time consuming to whip up a simple spaghetti but for someone they not trying to do all that and just want to get some quick food from the store lol.