When people got interested in fitness, some of the best earning opportunities cropped up in running gyms/ fitness centers. In terms of content production, instagram influencers peddling fitness also earned a lot. When the COVID-19 susides and if it actually turns out that the western world had it harder because of immunity issues, then there will be a lot of demand for "immunity building habits."

Also, the "back to nature" movement may gain traction. People with diverse knowledge and experience on these issues will be much sought after in such a future. If they can document and show results, it will be as good a way as any to get rich.