First part is only sorta true...second sentence is true, but they all can afford a used boat and are choosing not to...Sadly until the middle class expands and gains a share of global wealth we won't see anything but rickity go fast sport boats and luxury yachts 40' or greater
Boat builders stopped making affordable well built boats because the middle class could no longer afford to buy them...
Combined with the "economic stagnation" of the middle class, is that fact that WE have made building boats way more expensive than it used to be. The combination of increased environmental regulations, increased health and safety regulations on the job site, increased benefits and health care employers must provide, etc., have all combined to increase the cost of building a boat today.
Add to that the fact that we "enthusiast" sailors demand every more capable, high tech boats. Heck, everytime a new J/boat (or almost any new racer/cruiser) comes out, most of the crowd here pans it for not being significantly faster than the boat its replacing - and given you can buy that used older J for less than half the price of a new one...