Except that, as we've learned from the Martha Stewart mockery / trial, a corporation's stock price is largely tied more to impressions than to fiscal reality. One of those impressions is the image put out by the head of your company. If Trump's public image loses value, so does his corporation. By extension, so does his net worth, since it's heavily tied into the stock value.
Comparing his December stock price to what it is now (ticker symbol: DJT), he's more than doubled the value of that company, no doubt in large part to this second coming of his celebrity. So, yes, he has someplace to "fall".
Then again, maybe I'm just bitter that I didn't invest in Trump before the show started.