I think I can answer this because I asked this to Elon Musk around a year ago. Billionaires have higher anxiety and relentless stress. They just hide it from the world. Many develop mental diseases such as anxiety, disorders etc. Here is a link to my conversation with Elon Musk:
https://www.forbes.com/sites/brucelee/2017/08/03/elon-musk-a...