It sounds stupid but everything can't be overpriced because if everything is overpriced then nothing is. Overpriced means that the price of something is higher than its actual value, and this is the defining characteristic of bubbles. However, really ultimately the "value" of anything comes down to how much people are willing to pay for it. It gets almost philosophical, or at least theoretical. All calculations of value are relative, and ultimately boil down to how much people are willing to pay for something
I basically agree that the notion of overpriced loses its relevance if everything is overpriced. But as you yourself say, it all comes down or amounts to how much people are willing to pay for something, so there cannot be a reason the very existence of such notion in the first place. But since it, nevertheless, exists there should necessarily be a reason for its existence, right? As to me, overpriced relates to prices above the ones which would be there it the buying (selling) decisions were made via rational reasoning given the available info
That is, without being affected by market sentiment, hype, or hysteria
Yeah but what is a rational price for, for example, a bank stock? If they are all pretty close to having a price/sales ratio of 2 then would that be over or under priced? What if they were all 3, or 4? We can use fundamental data about an asset to determine its value, but only to the extent of determining value compared to other similar assets. Ultimately it all comes down to how much people are willing to pay. What makes one p/s ratio more rational than another?