Every decade has at least one of these buzzwords (multimedia, internet/ online, social media, mobile app, blockchain, cryptocoins, micropayment, delivery, ai,...).. They can be used to attract dumb investor's money but they have their useful sides too.

Ok. They are just buzzwords which outline a set of tools. They are worthless without a realizable concept with a benefit for the end-user. And the use of the right tool for the job. So, I'm not sure about useful cryptocoins and blockchain use cases (I wouldn't count financial speculation as particularly useful).