This is such a common leftist talking point that one can't help but chuckle out of exasperation.
Rich people may be a lot of things. Stupid with money usually isn't one of them.
The worst thing that a rich person can do is stow the money away in a savings account or under a mattress or whatnot. Inflation is, and has been for decades, rising at a faster rate than interest rates on savings. Every day that a person's money lies dormant, that money is being devalued.
Smart people with money invest. Investment clearly helps boost demand for labor more than people hoarding their cash.
The funny thing is that this is also a common leftist talking point against austerity in that they often encourage inflation as an economic stimulus because it rewards spenders and punishes savers.
But, yeah, it's no surprise that the mini-mind behind The 1619 Project can't grasp basic economics.