Tesla, SpaceX, etc., earning money would be taxed and that would impact Musk's value. They hide their money in individual compensation, you tax the individual, they hide it in corporate compensation, you tax them there.

You are not going to hurt them taxing corporate income. Business are even better at hiding their money. All revenue is channeled through 4 subsidiaries and a couple off shore accounts. Technically, all branches, except the one in the country with the lowest corporate tax rate, operate at a "loss".

See: https://en.m.wikipedia.org/wiki/Double_Irish_arrangement

You could try taxing revenue, but that will hurt businesses that are based around high volumes of low value transactions, such as discount retail.

You could try to tax business based on their asset value, but that will murder traditional businesses like farming and manufacturing, which rely on making a large investment in durable assets and then deriving profit over a long period. More importantly, it will not get any taxes out of tech companies, since most of their value is in intellectual property, something that cannot be accurately priced.