This is an interesting conundrum, actually. The big question at its core being:

Can you ever do enough good through philanthropy, so that it offsets the damage you had to do, in order to become a billionaire? Can even all the billionaires in the world do enough good with their money, to offset the damage done by a system, that allowed for them to become billionaires?

I, personally, don't think it is possible.

To give an actual answer: I think, the world would definitely be better, but unless those billionaires collectively used all the power their money provides, to do away with money and the possibility of billionaires altogether, I don't think it would amount to all that much.