Because if A and B start out at the same place, and A succeeds, then B lacks an excuse to justify his non-success. So B needs to tear down A in order to feel better about himself.
"in order to continue seeming to be a useful member of the group", I'd say.
And there're other strategies too, of course, one includes trying to help A become even better
Because if A and B start out at the same place, and A succeeds, then B lacks an excuse to justify his non-success. So B needs to tear down A in order to feel better about himself.