Is making a movie cheaper now than 20 years ago or do they take those cost savings and spend it elsewhere? Furiosa cost 168 million to make. Mad Max cost 350,000 USD to make in 1979 ($1.6M today). The value of streaming services is incredible in comparison, but with so much content being split amongst different services, most families are probably spending just as much as cable. Movie theatre tickets aren't cheaper today.
Feature length films are more expensive. Hell the character actors (not even the main star) gets more money for a film than the 1979 movies.
But does a computer generated film on YouTube that people put together cost the same? Not even close. It is a lot less than $1.6 million.