In any industry! Anywhere!
A while ago I was reading about a guy who picked up USA rust belt companies that were still making a good return, but were unfashionable and unsaleable. He bought them up as “Distressed Property” often for no money down. In a few years was a millionaire. Another Indian guy called “Mital” did the same with steel mills in the EU and Asia, and he was soon a billionaire. Of course you need to run these assets or companies well!
In the town where I often live (Campione, Ticino, Switzerland) there is currently a real estate depression with stuff going for 1/3rd the price of 5 years ago. Yet few buyers. Why? Because the “investing public” tends to buy only when “hot, fashionable stuff” is going up, and sell when it is going down. You must do the opposite! And only invest in things you control and run.
The secret is to buy or otherwise take over abandoned, distressed property that nobody else wants.