I guess it depends what stage you are at, and the type and quality of flying you like.

I don't have to buy an ARF to get something flying, my biggest problems include having enough computer memories to support the fleet I already have, and maintaining the batteries....

I guess building for me is almost a separate, but related hobby. It's not so much about the "look what I did", it's more about having an aicraft that I enjoy flying. I derive a large part of that enjoyment as a celebration of a job well done (personal pride in workmanship) but, also, being able to relax, safe in the knowledge that I have invested due diligence to ensure that my aircraft is not about to become a safety hazard.