We have been able to derive an immense amount of information about our universe from observations and probes but we're still incredibly ignorant. We can't even

We have been able to derive an immense amount of information about our universe from observations and probes but we're still incredibly ignorant. We can't even determine whether or not there might be a substantial dark body (several times the size of Earth) orbiting within our own solar system. That hypothesis is being used to try to explain other things that remain otherwise inplexicable even within our own 'little' solar system. Grand claims about being able to detect dyson spheres with a billion light years are just silly. And even when we do detect things reminiscent of what might be a dyson sphere there is a very logical and reasonable desire to not accept this and instead look for natural explanations. For instance KIC 8462852 was never fully explained and its dimming continues to this day. The only thing that stands out against it being an 'obvious' dyson sphere is the lack of ambient infrared, which we can attribute to a variety of factors, not the least of which being the all-encompassing 'technology we don't yet know'. But we don't do this precisely because when you start going down this road you can attribute basically anything to 'aliens' in the same way a religious person might attribute otherwise explainable events to a god. The point of this being that unless a LGM walks up to us and says hi, we're not going to attribute anything, seriously, to their existence.