OPEC decided not to cut production because they would rather weather the storm now and take short term losses (which only means less profit and aren't actually losses), in order to hold their marker dominance. The USA has started pumping oil at an alarming rate, to the point to where we were rivaling Saudi Arabia.
It costs us about 65$ a barrel to pump it via fracking. OPEC knows this. All they had to do was cut supply and oil would be 105$ a barrel again. They would rather charge less for their oil and hold their market dominance.
Why should we care? Give them the worthless paper for the oil, send it on over! Save our oil for times of need? Very capitalistic of me but its the truth.
Plus, it helps along our agenda with Russia, and increases profit margins in alot of oil burning industries.
OPEC knows that this is their only way of holding market dominance for now. It means much more profit for them to pump oil at 50$ a barrel for the next 5 years, than pump oil at 105$ a barrel and sell not as much of it and slowly lose their dominance for the next upcoming decade.