Name of a book featuring a race using interplanetary telepathy

Question

I am looking for the name of a science fiction book I read in my childhood. The story and clues as far as I remember are like that:

• There is an arid planet with a single but very tall building where the kin of "observers" resides. They have everything they need in this super-building so they forgot the existence of the outside.
• Apart from the planet of observers there are 3 other planets where civilizations of advanced humans, normal humans (we) and barbarians reside.
• The duty of observers is to observe these three planets and to prevent them to construct a spaceship.
• For that purpose they use a form of extremely-long distance telepathy booths located inside their building. By telepathy they can enter into (and control) minds of other people living in other planets. And they may sabotage any attempt to build a spaceship.
• The advanced human race long time ago ceased to attempt to build a spaceship. Barbarians do not have technology so only we try to do that during the timeframe.
• However, observers themselves had forgotten their original duty long time ago so they suppose these telepathy booths are virtual reality entertainment for them and they do not aware of that they actually control real people. So most of them control minds to make people do stupid things, or more serious things, like suicide and going frenzy.
• The story is about one guy in the observers found out the reality and eventually help a human to make space journey. There is also a guy, who is the leader of observers or something like that, fervently following ancient codes of the observers. (Sabotaging space ships; therefore, he always chooses to visit Earth.)

Do you know which book it is?

Answer 1

This sounds like John D. MacDonald's novel Wine of the Dreamers (aka Planet of the Dreamers), originally published (probably in a shorter form) in Startling Stories, May 1950 which is available at the Internet Archive. Maybe one of these covers will ring a bell. Plot summary from Wikipedia:

The book is set both on Earth (dealing with a top-secret military spaceflight project in an imagined 1975) and a far-away planet of humans able to influence Earth while they sleep, believing that the planet and all its inhabitants are simply part of their dreams that they can toy with. MacDonald described the book as "a symbolic novel of how when original purposes are forgotten, the uses of ritual can be destructive."