Opposite of buddhism
Well, first point... Things do not have opposites. Things simply are. Qualities have opposites, and to the extent that a 'thing' is seen as an epitome of certain qualities, we can point at other 'things' that have opposing qualities. So (properly speaking) Buddhism doesn't have an opposite, although there may be other movements that try to create exactly the opposite of the qualities that Buddhism strives for.

With that in mind, I'd point at any kind of fanaticism: political nationalism, religious fundamentalism, commercial exploitation, ideological extremism... any movement that intentionally distorts perception and understanding, and purposely creates turmoil, in order to advance some abstraction. I'll leave examples to the reader, so as not to politicize.