They probably do not get the same tax cuts: a “normal” person, making a paltry $250,000/year only reduces taxes by 24% of their giving, where the ultra-rich get 37%.

But the real difference is scale. A million people each giving $100 to their favorite charity is going to distribute that money more-or-less according to the community’s overall priorities. One person giving $100M to their favorite charity has no connection to the broader community and social goals. They supercharge that one thing, which takes attention and resources from everything else.