Concerning the comparisons with the .com bubble, well, just check the list of useless websites that failed. Teaching kids to read? Terrible user exp. by Boo.com? Books a million - too small market...
Crypto example of plain useless: SwissCoin, book example how not to invest. link. We made the Swiss Coin. It's cool because it's Swiss - buy it! Yeah... Right... Damn bubbles!