Hey there,

so let's address these things individually.

Crop circles. Nobody has ever managed to bring any proof that they are messages from aliens. And decoding, even if they were messages from outer space, would certainly not be as simple so random people could do it.

When it comes to the resources. Given sufficient time any sort of resource becomes a potential source of energy as it could be used to create black holes which could be then harvested for energy for trillions and trillions of years. Given an advanced civilization probably hopes to live as long as possible there is a good chance it would be hoarding every single piece of matter available in the universe to prepare for the time when stars will not be providing energy and it will need to be obtained in other ways.
Though I do agree that there are currently more readily available sources of energy in the universe.

When it comes to dark matter, question is yes, whether it even exists are there are some other forces at hand, but if it does exist another question pops up, is it ever usable as an energy source as it supposedly is almost completly inert apart from the gravitational forces.

And the last part, you realize that is just your own personal opinion non based on any facts that could be produced in front any sort of jury, whether scientific, juristical or even a jury of peers.