The F-35 is designed to be more expensive but cheaper to maintain. Fleet maintenance, especially in the US eats up a massive, massive chunk of the budget. So while the F/A 18 might be 1/3rd the price, once you count in maintenance, it might not be much cheaper...and it's last generation. There is a complex math behind it. There is absolutely waste, fraud and abuse in the military...but it's probably not as much as you think since the majority of military spending in the US is actually on pensions, healthcare, housing, salaries and maintenance of aging equipment. Things that in other countries are much cheaper or just not given to soldiers. Comparing the US to China and Russian (at least their public spending numbers) is so misleading. New research and projects is a drop in the bucket.
"Every gun that is made, every warship launched, every rocket fired signifies, in the final sense, a theft from those who hunger and are not fed, those who are cold and are not clothed.
This world in arms in not spending money alone.
It is spending the sweat of its laborers, the genius of its scientists, the hopes of its children.
The cost of one modern heavy bomber is this: a modern brick school in more than 30 cities.
It is two electric power plants, each serving a town of 60,000 population.
It is two fine, fully equipped hospitals.
It is some 50 miles of concrete highway.
We pay for a single fighter with a half million bushels of wheat.
We pay for a single destroyer with new homes that could have housed more than 8,000 people.
This, I repeat, is the best way of life to be found on the road the world has been taking.
This is not a way of life at all, in any true sense. Under the cloud of threatening war, it is humanity hanging from a cross of iron."
Address by President Dwight D. Eisenhower "The Chance for Peace" delivered before the American Society of Newspaper Editors, April 16,1953.