PC builds seem to short circuit everyone's pricing logic and drive any labor cost down to $0, just because they're willing to do it for free. Anything above that $0 is considered overpriced.
There are services that will build a PC for $200. It's entirely valid to ask where the money goes, and the answer is not the labor to put the pieces together. There's no reason to assume OP is being dismissive of that specific cost.
Part of the fun is planning, researching, putting together the pieces and power it on.