1. The true believers like labor theory of property a lot, and see having a mining rig as an extension of that(falliciously or no - there are plenty of critiques of labor theory of property itself). A bitcoin represents the "same amount" of effort relative to its value at a given moment in time.
2. As a lower margin use of energy premised on maintaining consensus, it has qualities that resemble perfect competition(in the economist's sense of that phrase) but actually go BEYOND perfect competition. While you can own a large part of the distribution or mining power, if you try to monopolize Bitcoin as a rentier you just end up forking it, as has been demonstrated by various events over the years. If people don't like your particular imposition of scarcity, they pull the rug in short order.
The second part is rather more important than the first, IMHO. Mining's meting out of energy usage as credit and the resulting price deflation is a way to get people on board with consensus and start engaging in speculative action, but there's a sense among the people interested in other cryptocurrency that that's just a starting point, and the development of distributed consensus tech itself is what makes this a "railroad" and not a "tulip".
"No rentiers" is really a pretty earthshaking concept, to the point where most of the people in the space can't see that light and look at the shadow puppets instead. But it does not seem to be refuted by anything I've encountered. While onramps and offramps to crypto are mostly controllable, this is still a huge upset to our models of what markets are or could be.
