Totally agree with your title. We are comparing apples and oranges. Here are the difference between the two.
Dot Com Boom
In dot-com era there was full understand what stock buying was. No hurdles or challenges to buy stocks as one easily could open a brokerage account and start trading. In dot-com era people were leveraging their principal to get more stocks. This is known as trading on margin. Margin was some where 4x principal and it was all legal service provided by the brokerage. The dot-com boom was mostly focused in the United States.
Crypto Boom
A lot of hurdles for investors to convert fiat into crypto, but admittedly getting easier. Crypto exchanges are plentiful but which coins they can trade varies from exchange to exchange. All people around the globe can get involved in investing in crypto.
Like you said crypto boom is at its infancy. The potential of reaching $5 - $8 Trillion in total market cap in my humble opinion is not if it will happen but when it will happen. Thanks.