What is it called when you value value something far beyond it's real worth?

When you value something far beyond its real worth, it is often referred to as "overvaluation" or "irrational exuberance." This phenomenon can occur in various contexts, such as financial markets, where assets may be priced based on speculation rather than intrinsic value. Psychological factors, such as cognitive biases, can also play a significant role in leading individuals to overestimate worth.