>Every philanthropist has a monopoly on the use of their funds.

And there are lots of them, not operating all under one central control, so they are likely to help local needs, compete in other spaces, and spread the effects.

> At least with tax-supported government programs, voters have representation on how those funds are used.

And then those funds are mostly sent to a big few items taxpayers hear about and not so much to any other needs.

Voters also have representation on how charity funds are spent, since voters are the people making donations. If anything, this means your funds target what you want instead of what others want you to spend on.