"If you ride several thousand miles per year, you can appreciate a high quality carbon fibre bike with top of the line components. It is all about the experience. Aerodynamics, handling, weight, acceleration, predictability, etc."
Don't get me wrong. If money were no object I would probably be on a bike "north" of 10k but the reality is that unless you competing at a very high level, the difference between a bike that cost 10K and 4-5k will never really be appreciated.
My Giant TCR Advanced was just over 4k and although the ride is softer due to the frame being CF and the Di2 shifting a bit crisper, there's not too much to point at that I would say makes it a better bike than my 2k Cannondale CAAD10 3 (Aluminum frame).
I loved my Giant TCR carbon. That bike probably saved my life. I T boned a fallen rider at 30 MPH whose tire had rolled.The frame snapped in three places and I went vertical landing on top of the bike. Walked away with a tiny scratch on my heel.
That TCR handled well and seemed to anticipate my climbing power shifting from leg to leg while out of the saddle.
However, The DI2 on my S Works Venge.....MMMMMMMMMM
Fast....very fast! I love the Speed!