I absolutely DETEST the "dark forest" theory because it's utterly ridiculous. It assumes that capitalism, imperialism, and conquest is universally normal, which is absurd. It isn't even normal for all of humanity! It's an aberration! And even if it was normal universally, the universe is so goddamned HUGE that there are basically infinite resources in the universe to use without even touching planets with life. Just mining the asteroid belt and the dead planets of our own solar system would probably take us thousands of years to start running dry of things. Then there are nebulae thousands of light-years across filled with so much water and amino acids and other good stuff that it would take a fleet of ten thousand ships with ramscoops a million years to deplete. There are massive, gigantic rocky planets with water and ingredients for life but are icy and dead or too hot for anything to live there, or the gravity is too high because they're so massive. An interstellar civilization could mine those as well, since these super-massive, vaguely earth-like worlds are much too extreme for complex life. Probably too extreme even for simple life!
The explanations I favor for why we aren't hearing signals from aliens are:
1. Aliens are out there and sending signals, but the universe is just so goddamned big that none of those signals have reached us yet, or they're too weak to ever reach us because they spread out too thin. I like this one because no matter how big you think even our galaxy is -- let alone the whole universe -- you are WAY off the mark because everything in space is bigger than the human mind can even begin to comprehend. And the signals we're sending out are already thinning out so much that I'm betting most of the oldest signals are indistinguishable from the cosmic radio background noise.
2. Humans are the only sapient species stupid enough to rape and wreck our own home planet for greed and capitalism. I like this one because I like the thought that war, conquest, imperialism, and capitalism are such aberrations that most alien civilizations are living their "milk and honey / hunter gatherer" lifestyle in peace, and it's only here on Earth that anyone went insane enough to invent war, conquest, imperialism, or capitalism.
Now these two ideas aren't even mutually exclusive. I could see agriculture and even industry developing without fucking up the planet's ecosystem or the aliens killing each other over resources. It would just take longer, with more cooperation, and focusing on mining areas and techniques that would do minimal damage to the environment, and then fixing any damage done as soon as possible.
Call me an idealist, but damn... if I was a better writer, I would be writing a sci-fi novel where industrial civilizations based on cooperation and sustainability arose, and were so common as to be normal. And Earth would be there, but I'd write a humanity that had realized they had no need to bother their neighbors because there's more than enough resources in our own solar system and in solar systems without any life of their own, that it would take millions of years to even begin running out of resources. And by then, hopefully humanity would learn good sustainability lessons both from their own mistakes and from the good examples of their neighbors. And the book or books would make it damned clear that humanity was singularly unique in the sheer speed and violence of their rising from hunter/gatherer to intergalactic civilization. We'd be the barbarians shocking everyone else with how fast we flung ourselves off our home planet. Before us, it would be unheard of for anyone to achieve an intergalactic civilization in less than a million years after the advent of writing.
Sure, there would be examples of civilizations that made it to an industrial level in less time, but the only evidence for any of those would usually be found by xenoarchaeologists digging up the ruins of such civilizations after they nuked themselves into extinction before ever getting so much as a probe into outer space. It would be considered a miracle or something that we managed to overcome our own barbarism. That "or something" making a great many other alien races decide to give us a wide berth in case we were just really good at pretending to be civilized. Basically, "humans are space orcs" but in a... not so good way. Not bad exactly, just... a bit like watching a civilization of the nastiest, most violent meth addicts manage to not blow themselves up, die of an overdose, kill all their own babies from neglect or abuse, or kill each other off for drugs or money, and then get clean and begin getting their lives back on track. There'd always be the memory of what we were, and the fear we'd fall off the wagon again.
Of course we're 100% still in that "violent meth addicts" stage. As long as capitalism exists, we're going to stay there. If we want to get clean, we have to get rid of capitalism and replace it with cooperation and sustainability. We have to start caring for the Earth and the ecosystem and helping it heal from our past mistakes.