You could have said that in every bull run. You could also say that about the S&P, if it's going to be worth more later why isn't it instantly that price now? And it's because it simply isn't worth that now plus different investors have different investment periods.
But you can invest in the S&P like that (through index funds), because the S&P tracks the performance of a rolling selection of stocks, not the backdated performance of a future selection of stocks that is unknown in the present.
Exactly, this is a fundamental fallacy of index investing—you can’t “buy the market” and any ETF that claims otherwise is a cleverly crafted leaky abstraction. The problem with leaky abstractions is that you usually have no idea that they leak until everything collapses...
BTC is different because it isn't backed by something like ownership in a company.
Also, there are different risks than equities. Equities have the risk of the company failing or being significantly impacted by many different things happening, while there are existential risks with BTC I feel these are often ignored or accepted as not applicable to most BTC investors.