From my point of view, it's choosing the custom "build" that's sometimes the most fun part.
It's like being a luthier without knowing woodwork.... Helping decide on the look, the sort of sound you'd like, the feel of the neck, the finish, the colour, whether to have "fairy" lights, the weight and on and on ....
Then there's the wait, the anticipation, have you made the right choices? Some you win, some you lose. In my experience it's a bit like gambling. If you can afford to lose a little (i.e. the build doesn't work out) then it's worth the gamble and it's addictive. It's been 2 or 3 years since my last build, but I'm already thinking a GB would be a nice build for my next one. Help! It's starting again.