Some people buy gold to make a return, but for the wealthiest people, it's mainly a way to protect their wealth. After all, gold represents purchasing power, without any counterparty risk. It is also a form of wealth that is completely outside the financial system and thus offers protection against a financial crisis such as that of 2008.
Another argument in favor of gold is that it is seen as a hedge against geopolitical risk. That is also the reason that countries such as Russia and China have accumulated a large amount of gold in recent years. With the gold, they can continue to trade, even in a doomsday scenario in which strict sanctions are imposed and bank balances are blocked.
The following infographic from Visual Capitalist shows which billionaires Buy gold as part of their investment portfolio. Of course, that's just the tip of the iceberg, because most people who have accumulated their wealth in a way other than investing will not be so quick to divulge this information.

Why the Billionaires of This World Buy Gold (Source: Visual Capitalist)