It's so weird to have authors try to make a comparison between real world currencies fictional currency buying an item that can't exist in the real world. The value is already a number you pulled out of your ass, why are you trying to make up another one as reference?
It's the same issue why the DBZ stuff still continue writing power levels. Despite being more of a detriment in the long term, people LIKE reading numbers.
I guess their readers expect that kind of irl sense of worth? Also the general obsession with very large numbers, because nothing says 'progress' like earning a fortune of 500 million Smackaroos or dealing 999999 damage one hundred times.