There is a big difference between a person who buys goods in large quantity and a person who buys in small numbers, for example a person can spend $50 in getting a carton of biscuits spends less than a person who buys the biscuits one daily. The consuming method of the poor is faster than that of the rich you will agree to this because the poor eats more than the rich.
In consumption, the poor eat more but for expenses for the food, the rich spend more. The poor can't afford fancy restaurants but the rich can afford that so they'll always visit them and many don't even cook at home anymore because they spend all their lifes being too busy to cook something for themselves to eat. For the buying of things in large quantities that the rich do is because they have the funds to afford those things but the poor don't usually do that. Being rich helps the rich alot because they can invest and forget about their investing while the poor will still have to come back to their investment because they have already exhausted the money they had before investing irrespective of them having emergency funds or not.