A hammer is a tool because no one but the hammer merchants gain financially if everyone were to buy a hammer. Crypto“currencies” are not purely tools but instead multi-level marketing pyramid Ponzi schemes because as soon as one has it they have everything to gain the more people buy it after them.

“Thirdly, early adopters mine or buy large proportions of the total supply at negligible costs while late adopters mine or buy negligible proportions at large costs. It follows that holders immediately have every incentive to get as many people to buy after them. Like stocks? Like stocks, but without the dividends or anything tangible in the real world [10]. Congratulations, you got yourself a pyramid scheme †.”

“† The stock market has largely become a pyramid/Ponzi scheme as well since most of the money does not exist and profits come from buyers or new entrants, i.e., the greater fool [16].” —Money corrupts; bitcoin corrupts absolutely, https://www.cynicusrex.com/file/cryptocultscience.html