The ultra rich will show up with close to zero income, because they don’t actually deal in cash. This isn’t the master plan you think it is.
Issuing a fine that is some multiple of the damages ensures that it doesn’t become a “cost of doing business”.
Issuing a fine based on the income of the person receiving it makes sense for a handful of civil violations, if you can keep it from being exploited, but it is very exploitable especially if you have a lot of non-cash capital that you can leverage without ever generating any legally recognized income.