how much better is a top end bike today than my 3 year old 26 inch wheeled carbon Nomad thats worth 2g I mean in actual ride performance.
Current pricing is especially ridiculous when you factor in the lifespan and depreciation of these bikes. My top of the line Moto and Trials bikes cost less, Last 3 times as long and cost half as much to operate in regular R[HTML_REMOVED]M. thats nuts.
New bikes are much much better in almost every way compared to slightly older bikes (and yes I realize that I called a 3yr old bike older). Mainly because of the geometry that they have finally figured out. Suspension has gotten far better now and is easily on par with moto suspension. I have almost completed two seasons on my bike with only two shock and fork rebuilds each, as well as two bearing changes and two drivetrains. Other than that I have replaced some touchy feely bits like grips, bar, stem, and I built another set of wheels (mostly because of the colour). I also ride several times a week, more in the fall. I also enter the occasional enduro and dh race on it too. Overall, relatively cheap to own.
The length of time a bike or moto lasts is how hard you use it. When I was racing moto I would buy a new set of tires every 2 weeks, sometimes sooner. New set for every race, mostly out of necessity. Once your dirtbike is set up its relatively cheap to keep going other than wear and tear stuff or engine parts that wear out. But getting into it as you know is much more involved than just buying a bike off the floor. You could do that and probably be fine for a long time, but there are some things you should probably add to your bike eventually.
Then a stock moto is almost certain to need suspension mods off the floor unless you are a squid or have some aptitude to mod it yourself. Suspension mods can be anywhere from let's say $500-$2000 typically.
My YZ250 had a Rekluse ($900), large tank ($200), skid plate/rad guards/pipe guard/hand guards ($350-$400), aftermarket pipe ($200), spark arrested muffler ($300), a bib mousse ($200), not to mention personal things like a bar, grips, levers, pegs, plastic, graphics, seat cover, gearing changes, several chains per season, plus all the maintenance costs (fluids etc). Part of the reasons I got out of it were the costs and the time. Way too much on either end.
I've seen plenty of dudes ride ten year old motos with nothing other than new tires occasionally and nothing else. It can be done but where's the fun in that? ;)