There are plenty of reasons why cryptos have value: media, hype, sentimentality, dependency, usability.. etc. etc. I guess with something like Steem Power, it's a functional asset that drives your experience on the network..
And tulips are very different things..
Tulips did have some real utility too and things get dangerous when the percieved value really exceeds the level of utility. I'm worried that SBDs are there and that's why I see this as unsustainable, but I'll be very happy if my worries turn out to be nothing.