As he rightly points zero sum would mean that whenever something attracts our attention something else is losing its share to fame. But the 'axiom' that fame is a zero sum quantity is be now measurable way true. In some cases if something excite as that means that we will loose interest in something else. But this is not general true. And this is the beauty of new ideas. They can generate interest from zero.

In addition he did not say that fame is infinite so as to make your laughter justifiable. He just pointed and I agree with him that fame is not by default a zero sum thing