That's not what I think 10x'er is though. I think a 10x'er is someone who enables the 'average' developer to become a 2x, 3x, 4x developer. This can be through writing some core tech, a library used by all, or through mentoring and guidance. The 10x'er can then become a 100x or even 1000x developer. The 10x dev is the person who picks up the really difficult or ugly stuff and says: "Hold my beer, I'll get that done" - motivating the team and helping them to keep velocity. They lead by example and explain to the team why they've taken the approach they have.

Sometimes people use the term Rockstar to define a 10x developer. I think that's a loaded term that comes with an 'arrogance' tag. The true 10x developers shouldn't be arrogant (beyond the base level arrogance everyone of ability has), they can and should be the glue that holds a team together and helps everyone achieve more.