See post 21. It’s not about comprehension. It’s about physics. Infinity outside of being a mathematical concept, is religion not science.
Infinity as a concept is supported by: no matter where you draw an end point you can always +1, in perpetuity. Thus it is non-finite. So if you are unable to define and end, it is thus infinite.
The question becomes relative to your location on that line. Does infinitely large, conversely become infinitely small? Can/does infinitely large occupy the same space as infinitely small?
Absolutely true. However, science has been unable to find an 'end' to the Universe, or to prime numbers. Science has predicted the size and mass of the Universe but had to come up with dark energy and dark matter to explain how galaxies stay clustered.
Their estimate on the size of the Universe is more 'faith' than 'science'.