They can fragment their holdings, but the different admins of the different stake pools may vote for different projects ... and they don't really depend on the stakes of certain stake holders because anyway their pools normally won't surpass a certain size ...
I don't say one couldn't circumvent these hurdles at all, but at least it's an interesting try, isn't it?
I'll have to dig up sources, but I do recall members complaining that Cardano had been over-run by cartels very quickly. Not sure what the feeling is now.