You're on the fence about aliens but take demons seriously? You have to understand that they can be one in the same. Extradimensional beings/entities can be defined as "aliens" as "demons" and as "angels".

If a being not of this Earth presented itself to you without making its intentions clear, how would you be able to define it as an alien vs a demon vs an angel?

There is an insane amount of evidence (of literally all kinds) that these beings exist and have existed alongside humanity for thousands of years. Some have good intentions and some have bad ones, but one thing is for certain: they are very real and relevant to the grand scheme of things.