Unless the billionaire in question is extremely vain, they should absolutely want some of their paper wealth to vanish temporarily since it is an opportunity to

Unless the billionaire in question is extremely vain, they should absolutely want some of their paper wealth to vanish temporarily since it is an opportunity to accrue more real value stuff at a discount for those that have large amounts of either cash or cash equivalents on hand. All of their paper wealth will appear again in the next upswing.