Even a non-electric full suspension MTB can easily cost well over 5k. What people don't often realize is that these are extremely high quality top of the line products. There's not a huge difference in the quality of components between a 5k "consumer" level mtb and one that a professional rides in a competition. Cheap mountain bike from walmart simply just can't handle the beating that a more expensive one can. The cheap bike literally falls into pieces during the first downhill ride.

I can see it both ways. My daily driver is a converted $100 Walmart bike (the conversion kit & battery cost +$500). It's held up okay, but I've had to put a lot of labor into it.

The only things original on it now are the frame, seat, crank, and one pedal. Still, at 4600 km, I've put less than $1000 into it, so you can get into it pretty cheap if you're commited and your needs are simple.