Just look at WW2: Germany had some fantastic equipment, but they couldn't field it because they didn't have the fuel, spare parts and the maintenance capabilities available. A tiger could kill 10 Shermans, but the Americans could always bring up an 11th Sherman.
For decades we have been able to afford complacency - we strike when we're ready against people who mostly can't strike back. We can afford to be wasteful because we have so much more than anyone we would go up against. No one is seriously threatening our ability to keep our military going. But militaries need to be prepared for peer conflicts where someone could give us a run for our money.