No, just those who try to swindle others by selling them shares of dry oil wells, water-powered cars, ponzi schemes, etc..

No sane person would invest in cash, unless the money came from some illegal activity, or one is trying to evade taxes.

Real estate, and stocks of large, established and diversified companies are usually a safe investment.  Even if they are overpriced at some point, and may crash eventually, there is a limit to how much they can go down before hitting their fair price.  Since they are material property, their real value will not be affected by inflation.  For those who are too lazy or small to use those investments, there are many bonds and investment funds that are somewhat riskier and offer smaller returns, but will still protect from inflation.

I don't have much to say about gold, except that it seems to be vastly overpriced, and its price charts are not nice at all.

No one can honestly predict the future of bitcoin.  It may rise again to thousands of dollars, or it may be superseded by something else and go down to zero.   It is a big gamble, a lottery ticket with unknown odds.  People should be free to gamble, but must know that it is gambling and not investment.