Bill Gates is required by law to give away 5% of equity in his foundation every year otherwise he would lose charitable tax-exempt status from IRS... so yes, he gave away billions but at the same he avoided to pay billions in taxes to government by funneling most of his wealth into his foundation.
So the whole comparison between him and the government is pointless since it's the government that made it possible for Bill Gates to even do charity at this scale by sacrificing its own tax revenue.
If Bill wants to give away billions to good causes and as a side effect he gets charitable tax-exempt status then I'm more than happy with that. His money is being far better spent than his tax dollars.
shrug pay taxes and have your money spent in ways you disagree with, or, run a foundation and spend your money instead on goals that you do agree with. Sounds like a tough decision...
Are you making the argument that it would be impossible for him to do any charity if he was taxed or that he wouldn't do the same thing if he had to pay taxes?
So the whole comparison between him and the government is pointless since it's the government that made it possible for Bill Gates to even do charity at this scale by sacrificing its own tax revenue.