Investments are based on investing in the work of others. You have bonds which loan money to companies who make sure of those funds and pay you interest out of their profits. You have equities which invest in companies and then share in their profits.

Crypto doesn't have any underlying assets. There's no company doing work generating profits to generate value, interest, or dividends. The value is wholly based on confidence in th value of the cryptocurrency. There's no real value or work being done to convey value. Because of the way it generates value it's more like a Ponzi scheme than an investment.

Because of that I don't like seeing people recommend it as an investment because there's no floor in the value. There are no assets or businesses or profits to drive the value so a serious crisis in confidence could see the value fully collapse to zero.

With proper investments there's a floor, the value of the underlying assets within the companies. Shares may trade above that based on expectations of future success but there is a floor and you know that in any market crash your assets may become undervalued for a while but they exist as shares in tangible companies with tangible profits and assets.

tl;dr: it's too close to a Ponzi scheme and there're no assets or profits driving the value.