Obviously, you do not watch anything other than Hindi films, so you are excused for rating an overacting mediocre actor as no. 1. In the world!! Forget it, he's not no. 1 even in India, where Kamalahasan, for example, is a far superior and versatile actor. (And, I am not a Tamilian, not even from south.)
Coming to the Forbes ranking, it is based on pay, web hits, press mentions and TV mentions, and all these are counted largely only in terms of the USA and generally the Western world.
Please realise that for Americans, the world ends at America, like Hindi movies is the end of world cinema for you.