I suspect that the real truth is a little bit of all those reasons.
My only other issue is the reliance on the Kardashev scale for measure of advancment. I think of it like judging civilisation vs barbarism based on how much food people consume. Especially when you consider it doesn't take into account population size. The sci-fi writer in me can imagine some sort of non sentient fungal mat growing in space that envelops a star at around the venusian orbit level and uses the entirety of the energy of a stars output. Meanwhile a single person could achieve immortality, have a matter replicator, and spend their eternity self contemplating, exploring via slow boat craft, and exploring the works of cultures encountered via vitual reality... and they'd use less energy than any nation on earth today.
Live content within small means. Seek elegance rather than luxury, Grace over fashion and wealth over riches.
Listen to clouds and mountains, children and sages. Act bravely, think boldly.
Await occasions, never make haste. Find wonder and awe, by experiencing the everyday.