I'm an extremely bad reader (and was a KS backer for NRxaB) but I'll see what I can do...
The obvious starting point: stupidity. Both bitcoin and the alt-right (and there's overlap through the libertarian nexus) are full of idiots falling for one another's grifts.
But that's a bit too general and a bit too smugly complacent to let lie. So we can move on to idealism as a point of similarity. Moldbug hated Marx but Marx haunted his work, and the same theme comes up in the Austrians essay - a bizarre cloud-castle built to rampart out commies.