I believe that asset prices are mostly rational, and that the best fit line all the way through stock market valuation history is mostly explained by the risk free rate and dividends. There are momentary lapses of rationality, which is why "momentum" is considered a factor in stock market valuation, but you can make a perfectly rational guess that the future will be better than the past, more productive, and have higher dividends, justifying a bet on market beta, at least.
But there are lots of things that have idiosyncratic risk that can pay off big, like you buy a house in a shithole that turns into the next silicon valley, or you buy a scratch off lotto ticket and hit it big, or you buy some random internet meme shit like BTC / Ethereum, and it turns out to pay out when most other pick six bets didn't. That's ok. Even counting the winners, it still isn't rational to make bets on all these random assets, especially when their value is even further from reality than pokemon cards because cards can have real sentimental value.
If I but a total stock market index, I can say I think the future will be better than the past, with higher dividends. If I buy BTC, I can have a story about how some other sucker will buy it from me for more, but I can't say why they will do it other than hype. So maybe I'm right. Maybe my birthday is the next mega millions numbers. Who knows.