I think one of the reasons that he writes this is that cash in the hand is extremely appealing if you are not in a good economic situation.

For instance, I have some savings, so I can keep the wolf from the door, and I have friends and family so I always have a place to stay and at least something to eat. I won't freeze or I won't starve.

Cash on the barrel every night is extraordinarily appealing to those who have to buy antibiotics for their kids right away, or who have to make the rent that day.

I've never driven Uber, but I am given to believe that they settle up debts every day. Just like why waiters/bartenders like doing what they do. They get a fistfull of cash every day.