That's kind of cheap for my liking.
I bought mine used, but it was a $5500 bike new. $4000 is about mid range in "good" mountain bikes actually. Carbon frames, complex and expensive suspension, hydraulic disk brakes, hydraulic adjustable-height seat posts, carbon wheels, and everything lighter (more carbon). It's the same as how many on here have $1000 fly rods, $500 reals, etc. and any non-fly fisherman would look at you like you're crazy.
Just like fly gear, buying a better bike won't make you a better rider or even mean you'll have more fun. However, for experienced riders that spend a lot of time on their bikes and have the skills to appreciate them, the difference is huge.
Also like motorsports, the technology is driven by competition where cost is not the primary factor. This technology starts in those $8-10k race bikes (whether it's cross country, downhill, or anything in between) and slowly trickles down to the lower models. Just like cars though, this means the "lower-end" models are really good now, but also cost a lot more than they used to.
Just like fly gear, buying a better bike won't make you a better rider or even mean you'll have more fun. However, for experienced riders that spend a lot of time on their bikes and have the skills to appreciate them, the difference is huge.
Also like motorsports, the technology is driven by competition where cost is not the primary factor. This technology starts in those $8-10k race bikes (whether it's cross country, downhill, or anything in between) and slowly trickles down to the lower models. Just like cars though, this means the "lower-end" models are really good now, but also cost a lot more than they used to.