Prior to World War II the vast majority of telescopes built around the world were funded by wealthy people with an interest in the heavens above.
However, after the war, two significant developments in the mid-20th century caused the burden of funding large astronomical instruments to largely shift to the government and academic institutions. First, as mirrors became larger and larger to see deeper into the universe, their costs grew exponentially. And then, with the advent of spaceflight, the expense of space-based telescopes expanded even further.
But now the tide may be turning again.
