This throws a lot of people for a loop who want one source of objective truth for everything. But markets don't work that way: they're just deals between individual people, which may or may not become public. If somebody else makes a deal that you think is absolutely crazy, it is objective truth for them but absolutely irrelevant to you.
Personal finance works the same way. I know a few folks who were momentarily multi-millionaires during the dot-com boom; then valuations came crashing down and they were completely broke. We also tend to think of the value of a dollar (in cash) to be stable, but as anyone who lives in Zimbabwe can tell you, that's not a given.