Many people view the existence of billionaires as a profound societal flaw. The accumulation of such obscene wealth by an individual is only possible because of systemic problems which prevented employees from capturing their fair share of their productivity, prevented competitors from entering the market to lower margins or prevented customers from being able to purchase at lower prices.

It's a good thing that he's giving away 4% of his wealth. He'll still have $140,000,000,000 left after this donation though, which is relevant context.