The calculations are based on income, which equity (until sold) is not. In most cases even then (capital gain).

Stock also varies a lot in price/value (sometimes being nearly impossible to value, say for private companies) and many arguments can be made (up or down) as to its value or potential.

A good lawyer can start to get traction there of course, and it won’t get ignored, but it is not easy compared to, say, a $5mln/yr salary, or 5 years of bonuses of $10mln, which you can just plug into the calculator and go.

[https://childsupport.ca.gov/guideline-calculator/]