Tim Cook, CEO of Apple Inc. Adam Jeffery | CNBC

Health care is notoriously complicated. But it's also a mega-market rife with waste and inefficiencies. That makes it hard for big tech companies to ignore. In the past five years, Apple, Amazon, Alphabet, Microsoft and Salesforce have all made big moves into the sector, as evidenced by a string of recent hires, product announcements and acquisitions. Apple CEO Tim Cook summed up big tech's attitude to health care in a recent interview when asked about whether the company's focus on health stemmed from altruism, capitalism or both: "We’re extremely interested in this area — and yes, it is a business opportunity." Tech companies such as IBM, Microsoft and Alphabet have tried to fix health care before and failed. As Seattle-based health investor Dave Chase notes, some of these efforts, like Google's ill-fated Google Health, failed to get off the ground, despite an investment of millions of dollars in talent and resources. But Chase says these companies appear to be learning from their mistakes. Instead of going broad, tech execs are focusing on the corners of the market where they can do well. "It's a misnomer to think of health care as a multitrillion-[dollar] market," he says. "Really, it's a thousands of billion-dollar markets requiring a range of go-to-market approaches."

Playing to strengths

These days, tech companies are playing much more to their strengths. Just look at Alphabet. Instead of going it alone, Verily, its life sciences group, is partnering with health-care companies for a wide variety of R&D projects. It benefits from the expertise of companies including Johnson & Johnson and Sanofi in areas such as regulation, while it stays focused on the engineering, design and product development.