Thus highlighting the difference between monetary value and what is actually useful. It's a difference people get confused about too often - thinking that the most important thing on the planet is the economy; thinking that everything is fungible because it has dollar value. It's all fun and games until we hit resource limits of the planet. Or kill someone. Our economy sucks at pricing in the fact that while we can safely run out of tullips, we can't safely run out of clean air.

Your definition of 'actually useful' is going to be different than everyone else's. Economic value is the only objective value we have.

Assuming that humans make rational economic decisions. Which is false.

The only way to define an economic decision as rational is if it optimizes for the market value. The rational thing to do in the bulb mania was to produce tulip bulbs.