I think your problems lay with a lack of understanding of what money is and what it is not.

There was a time when currency was exchangeable for gold and or silver. Some tribes use specific stones. Regardless, you are correct in pointing out that we live in a world where 'fiat monetary' systems rule the roost. Fiat systems are not exchangeable.

The brings up your question of why therefore should I place any value on these slips of paper and cotton? Money is a unit and symbol of exchange. It has no intrinsic value. It derives its value from the productive efforts of individuals. It is a facilitator.

To give you a stark example, what if you had 1,132,123,123,231,123 dollars but there were no workers? In this world you would have a ton of money but there would be no products or services to purchase. The money is useless.

Which brings us to the morality of money. If our actions define our values then what we spend our money on defines our morality. It is the act of giving up your efforts in time and effort for the time and effort of another.

Why do we desire money? Because we desire others values.