People like us did not make the market go up. Investors and speculators did. They always do that when the next hot thing surfaces. Then, it's like a feeding frenzy. Everyone feels that they need to get in before its too late, or they want to get in to "Get a piece of the action". As a result, there is rapid appreciation in value, and the investors make a killing. People start pulling cars out of garages, barns, fields, junkyards. The market gets flooded with vehicles, increasing supply, which decreases demand, and slows appreciation. Once the market tops out, and the appreciation slows to a halt, the investors and speculators quickly get out of the market and take their profits. Increased supply causes prices to fall, causing other car owners to panic and try to sell their cars before they lose money. Remember that many people used home equity loans to buy playtoys, thinking that they would continue to go up in value. It's just like the stock market, or the housing bubble. With the economy worsening, and us sliding into a recession, it will get even worse as more people try to cut their losses because their homes and vehicles are no longer worth what they paid for them. If you watch the auctions, you'll see that the 50's and 40's cars, along with vintage racers, are now starting to appreciate. See, that's what the seculators and investors do. They find a lower value item, and create an artificial demand for it, causing it to heat up.
Will the 60's & 70's Muscle Cars go back up in value again? I doubt it. Believe me, they haven't bottomed out yet. Too many factors against them coming back. As long as you own a car to enjoy it, none of this matters.