Thats a matter of opinion really. I dump some decent cash in my bike. It takes the abuse of technical trails. If I had gotten a cheaper bike I would have snapped the frame by now (well maybe two or three)....
quality of bikes required are relative to the area you intend to ride. You may not see value in 'expensive' bikes, but that doesn't mean they don't hold value. Anyone from Ca, Wa, BC, Co or other quality terrain areas will likely vouch for that.