To add to the mix on this- access to credit. I suspect, going back a few years (decades?), that kit was determined by what you had spare month-to-month, and how long you were prepared to save. It seems there is easier credit is available nowadays, giving quick access to valuable equipment. Less obvious on bikes perhaps, but jumps out when looking at the quality of cars in my area. Ultimately shifts the decision from what people need to what people want.
Other thought - I'm not sure there's huge difference year-on-year in performance, but there has been a real improvement in bike design & performance over the last ten years. Not road, but have recently gone from a good pre-2010 hardtail MTB to a good mid-range full suspension, and the difference is impressive. And I do find riding more fun as a result - smoother trails are faster, which gets me my adrenaline fix, and can tackle more tecky/steeper trails without quite so much fear. So I think my splurge is justified :).