Medicine and tech are where the big bucks are according to all the venture capitalists. Listening to their analysis, they'll dedicate a chunk of their portfolio into industries that pose high growth potential or are resistant to recession. Tech poses high growth, and medicine in particular has government subsidy backing so they're a bit more resilient to economic turmoil. I've seen VC's dump their money into Silicon Valley startups which torch money for years before they are profitable, if they ever reach that point. Others have the sole interest of being bought out by larger companies.
Even picking out a few companies to invest in highly profitable industries is a bit of a gamble -- tech companies flop every day unfortunately. To your point -- diversify!