Since you can easily cross post to nostr, it seems like pure upside to post here. There are two explanations that come to mind, after wondering about this quite a bit myself. 
1. Ignorance of some variety: The big bitcoiners don't know about SN or don't see learning how to use it as worth their time.
2. Conflict of interest: They see Stacker News as a competitor to their own brand and don't want to promote it.

Undisciplined

Why don't the known bitoiners shill SN more?

stack_harder

It's a good question. I have always wondered why so few bitcoiners in general use SN. Should be low hanging fruit. 