I don't see any crank (or any handlebar, saddle, or wheel set) ever selling for tens of thousands of dollars as a collectible. I could be wrong. The way inflation is going, $10,000 might soon be not a lot of money. Certainly some very rare, special, and exotic bikes will command high prices in the future, just as they do when new. But I doubt bike stuff generally will ever be as collectible as vintage sports cars or baseball cards.
I agree with those who say it's foolish to buy bikes and components as an investment.