As has often been pointed out, Lennon was not sufficiently moved by his own lyrics to share his wealth with the world, as he called upon the rich of the world to do in the song.
Well, he did live in New York City in the 70s. The tax rates then were extraordinarily high; he would have paid New York City, New York State, and Federal tax, probably well north of 50%.
He also bought all the cops in New York City bulletproof vests when the city was broke and couldn’t afford it. That’s part of the reason the cops made such an heroic effort to keep him alive when he was shot.