Your argumentation isn't logically sound because you're missing one very important part: it "goes black" for YOU. If you died now absolutely nothing would stop for me, so your basic assumption that everything stops is already wrong.

If your argumentation was true, then this would also be true for any device with any form of sensory input.

A laptop being shut down and never turned on again also makes "everything go black" from the perspective of the laptop itself. Does that now mean that the laptop in question was the only true being in the universe? Obviously it doesn't.

And you as a human aren't special in any way shape or form either. Your singular experience ceases to exist, nothing less, nothing more. Same goes for any experiencing being that ever existed.

Everything "went black" for every single person that came and went before you.

Also it doesn't really go black. It goes nothing. Your experience is gone, thus you couldn't experience black either. Everything, including the perception of time, stops for you, thus nothing ever can happen - from your no longer existing perspective.

Now to make it interesting again: Your basic idea of being the only true being may still be true.

Scientifically speaking there is no way to prove or disprove that you aren't hallucinating everything, including me. Even if I lay out the perfect reasoning of why I exist to you, you could've just as well imagined it. From my perspective this obviously means that I may very well just explain to a hallucination of mine how I could be a hallucination of it.

This goes for every single statement that is outside of science though. God may exist, you may be a Boltzmann Brain imagining reality, this may be a simulation, this may be a single version of a multiverse like a decision tree - all these "fun to imagine" scenarios are outside the realm of science. Thus they may very well be true (or false), but we will never know.

Which is also why science never states absolute certainty and only models what agrees with observation.

Atheism doesn't propose such a thing. It's just the philosophical standpoint that denies the existence of deities. That's all. Topics such as afterlife, souls and other metaphysical stuff is outside of its scope. There are schools of Buddhism that deny the existence of god but believe in reincarnations.

Atheism isn't a believe system. Same as "not stamp collecting" isn't hobby. Not believing in god doesn't mean a person can't believe in other supernatural stuff (UFOs, chakras, whatever).

BTW, the view that you describe about reality not existing outside of your own mind is called solipsism. That position stands on epistemological shaky grounds though.

Sorry but this is pretty nonsensical. First of all it shouldn't be this very far-fetched concept after we die according to atheism. We already have not existed for billions of years before we were born. It's just a matter of returning to the state of non existence we were in previously.

So if that whole concept of death is true then you were the only real being in the universe? I can kind of see what you're trying to convey but those are a poor choice of words. I think a better choice of words is that you're simply literally the main character. Which lots of people have already made that point before. There's a good Joe Rogan motivation clip that makes that point. But just because each person is the main character of their lives doesn't mean that everybody else isn't real.

But yeah it's kind of obvious that everybody should be the most important person for themselves. The typical exception is parent's love for their children. I will give you an interesting example of a thought i had that lines up with all of this quite perfectly. Back when i lived in Israel when i was younger i gave myself this thought experiment if i had to sacrifice myself to save the entire country of Israel and the answer i gave was that i wouldn't. It's because military is mandatory over there and that's why i was thinking about it. Because i so didn't care about protecting Israel i managed to get out of serving in the military though that's no easy feat. (had to convince them i was seriously suicidal)