Stealing most of someone's cock size but granting them ability to do the same to others, except they only receive half of what the other loses.
They go rob two others of most of their inches just to barely break even, and those two later discover the same ability. The cycle goes on and on, slowly wiping out most of the endowment of the whole population.
Turns out quite a lot of size comparison kinks develop when everyone's fighing over the stuff, and those only grow stronger when the more prolific and dominant thieves get humbled too.
In the end, only you keep a cock any bigger than a nub, and suddenly you have a whole horde of adoring, nearly-null subs to attend to you. Maybe one day, they'll figure out how to turn the tables, or maybe they'll just beg you to leave them totally smooth.