Compare the Mass of Mars To Any Asteroid
Fair for gravity, but resources?
Even if you took the mass of the top 1 mile it still would still be far more massive than any NEO.
The advantage of NEO's in availability of any single resource is dwarfed in comparison to Mars by the dificulties in getting to the next pile of resources and the total number available.
NEOs are a good source of raw material for a space based civilization. Problem is we don't have one and NEO's can't serve as a basis for one all by themselves. Mars can.
see ya
