Probably the last couple decades saw custom PC building decline in market share as prebuilt solutions became mainstream, but perhaps it's seeing a resurgence now that most consumers have moved from focusing on computers to focusing on smartphones as their personal tech hub.

Now that prebuilt PCs tend to be cheap and limited, anyone who wants something better needs to build the machine from parts.

Prebuilt pcs were cheap in the '90s and '00s as well. Premium brands like AlienWare still exists for gamers.

But in the 90s laptops were insanely expensive. :-)

Not a recent trend but online communities act as a catalyst.