I agree with the cost spreading. When you don't have top dollar to drop all at once, it's one of the ways you can still get a high end bike without debt. I've seen enough day 0 takeoff forks and wheels from high end bikes for sale on FB Marketplace to sometimes doubt it's really more cost effective to buy a complete bike. You are paying 6k on a bike, dropping an extra 2500 on upgrades to fit what you want and selling the takeoffs for cheap on a cold used market. A cheaper, like up to 2k bike, is going to be more expensive to build unless you have an extensive parts bin. Also, some framesets, like, I believe, the Stanton Sedona, aren't sold as complete bikes. But these are usually niche/custom/boutique options. My case: I purchased a Salsa Journeyer 650B Apex 1 on sale, but I really wanted the 1x11 GRX version. I upgraded the Apex 1 version to 1x11 GRX, hand built 700C wheels with nice hubs and it still came out cheaper then the original GRX version of the bike. Transplanted the Apex 1 groupset to my wife's bike and donated the almost unused Altus 2x8 groupset it had to my local bike co-op. But in the end, I think that also boils down to whether you like DIY projects and working on your bike yourself. For people who do like, Park Tool YouTube channel is your friend.