The OP missed one realistic theory.
Every civilization that advances to the point to be able to travel and communicate with other civilizations.....
instead develops virtual reality systems so good that the civilization's progress gets caught up in amazing fantasy worlds and real-life exploration loses all funding and energy.
Every civilization that advances to the point to be able to travel and communicate with other civilizations.....
instead develops virtual reality systems so good that the civilization's progress gets caught up in amazing fantasy worlds and real-life exploration loses all funding and energy.

more or less.