Oh, that, Inadequate. You mean mathemagicians? Because in physics space is but an abstract relation not a substance that can expand. But in mathemagic they use the trick of multiplying zero by zero while introducing all kinds of fractions by sleight-of-hand. The fractions multiplying imitate a meaningful physical activity. They imagine all kinds of lines stretching. Vectors, tensors, lines of force and suchlike and then forget to tell the public that the lines exist only on paper. That's how it's done in a nutshell.
So, to summarize: the big bang is not impossible to conceptualize because as you know perfectly well lots of people are perfectly able to conceptualize it; but rather than admit this you would prefer to spout a lot of crazy bullshit about a subject (mathematics) of which you possess no actual knowledge.