The vast majority of it was driven by speculation and outright scams. The few who were genuinely trying to make a currency couldn’t make something competitve with existing systems, as they all ended up with the same problems and then some. Usually, blockchain based systems are very slow, expensive, centralized (in who has control over it), hard to regulate, and insecure. The only real advantage they have, is being harder to modify records for, meaning they’re less private and more traceable, if that can even be considered a plus for currency.