I love building computers, and building my current system reminded me what happens when you stay out of the game for a decade.
I often recommend pre-built for people, because building is something I enjoy, and they probably just want something out of a box and ready to go. I understand that, but there are still savings in building it yourself, as long as you know what you're doing.
Though sometimes you can get caught out

When I built my server back in 2012 I fell for the New Egg description of some ram that would work in any server well it was actually registered ECC whcih wasn't supported by the Xeon 3s and I fucked up a motherboard in the process so it was rather expensive in the end.
With the money I spent I could have ended up going for dual processor E5 and wouldn't be wanting to replace it now

But supermicro board and case and the fucker has run almost none stop since I built it.
Fortunately the next system I build wasn't an issue and it's going (Core i5, 16GB on an Asrock ITx board in a bit fennix case). probably could do with a video card as the integrated graphics are struggling with some games.