He said that cash being a debt is trash in the long run. In a capitalist system, capital that isn't working is just delaying claims on the future while not helping in future production. Savings is a ponzi scheme?
In a cosmic view of the long-run we are all dead anyway, but paper not put to work doesn't produce anything. Try planting a bill, will you see a tree?
If there are more claims than there is production in the future then your paper is worth less. Monetary inflation makes cash trash, is a valid way to read what he is saying.
But investing the money is what Mr B wants you to do. Whether you do that in equities, like he did, or in fixed income, say municipal bonds or CDs is really up to you. Cash under your mattress is trash. Paper doesn't make paper.
Oh and btw I am of the dogmatic conviction that banks should not be paid for deposits with the central banks, because this is paper making itself and growing its mass without productive use. These payments should stop immediately. Cash hoarding is killing them everyone, the banks included.
In a capitalist society, capital that is not working is dead weight. Capital that is not working IS trash.
Don't keep cash under the mattress, put it to work somewhere.