Until recently, with the advent of billionaires who made their fortunes selling fluff, instead of things, no one could afford to undertake these massively expensive projects except governments.
Bezos, Musk, et al now have the billions of dollars required to play in space.
The real problem is/was a lack of interest in the public. Space exploration died after a few moon landings and we became transfixed with serving our own self interests instead of expanding our minds.
Not much has changed since then and the biggest yield from space has been communication satellites - so we can talk to ourselves.