The reasons vary. But some if it has to do with gas fees, which refers to the unit that measures the amount of computational effort required to execute specific operations on a particular network, like Ethereum. Some of it has to do with projects that they're associated with. Like Mana for instance, being associated with Decentraland.org and being used in Facebook's metaverse. However, some of it like anything is speculation.
So - betting on their networks and uptick as well as how efficient they are at generating the juice ?