Except for thief, lottery, inheritance, marriage, or trickery, money is made when you've created value for others. Repeat and scale multiple times over, and you've not only made money, you've contributed and made others lives better, happier, more entertaining, or less stressful, etc.
Using their businesses as leverage, most of these billionaires have made their fortunes creating billions of dollars worth of value for the masses. They deserve every penny of it.