Government is often significantly more effective at spending money for charitable works than private charities due to all the overhead involved in running charities. Further, as a private individual I dislike that my tax money is used to in part fund charities that I strongly disagree with.

If you want to use your money to support some private crusade that’s fine, but why must we support anything anyone thinks as a worthy cause? It’s in effect a blank check without meaningful oversight. Their are for example homeopathy charities whose donations are tax deductible.