Yet today, half the world with computer access uses Linux, directly. And the entire world uses it indirectly.
I wouldn't call my Android phone or smart TV a Linux box, and when I browse a website there's no "served by Linux" logo :) end users simply have no idea nor care about any of this.
spectramax was comparing it to Linux on the desktop (which never really became mainstream).
It might be that bitcoin is similar to linux - used as a backbone, but not customer friendly enough to ever be used directly by customers. Like maybe banks use it to transfer large amounts of money between each other or something.
Bitcoin is far far away from such success.
That's my point; I think this is a possible and not unreasonable outcome for Bitcoin.