I mean it's pretty well established that poor people spend money, rich people save it.
Money that working class people get goes back into the local economy, creating jobs and stimulating growth, while with each transaction the government skims off tax. Even once they're comfortably paying for all their necessities, they still splash out on "luxuries" when they can afford them.
Contrast that with rich people who store it in off-shore shell companies in countries you can't touch, or just pay someone to estimate the value of a piece of modern art as however many million they owe in tax and donate it to claim back against tax.