What makes it difficult for me to believe that the void or empty space beyond the universe is infinite?

if a big bang happened. did it instantly go everywhere? or was there some place it is still not, because it keeps expanding? where is it expanding into? if not a place without it? perhaps you doubt infinity, which is just a way fo saying a very large number, that we are not concerned about picking a particular one. a lot of people do not understand infinity, very well at the very least, so are confused when people talk about generalities. I mean are you paying attention to every little thing going on, out there? if you are not observing it all, you cannot say for sure what is happening, just guess work, and theories. trust is hard to come by, sometimes. not easy to convince people of what they are unsure about.

Because you're wicked smart and know that there is no space beyond the Universe. Space is a property of the Universe. .

because infinity is a made up thing. We just gave it a word to represent an other wise unfathomable concept.You also can't prove it, which is why it's called the Big Bang Theory, so you're a skeptic.

there is nothing beyond the universe

You can't prove it.

What makes you think there's a void?