Minus capital expenses, various sorts of outsourced work (art, accounting, ...) and fees left and right (bank, chamber of commerce, ...)

In a startup phase you can avoid most of them, and they're all not very big but still add up.

Also, this is without pension contributions (if I'm following your calculations correctly?), whereas an equivalent full time job would include them.

Still not too bad, but not an equivalent of what one would make in a 'regular' job, even when keeping risk discount factors low.