​In today's knowledge economy, people are often a company's most valuable asset, and losing talented employees can be extremely expensive.

Laszlo Bock, the SVP of Google's People Operations and author of new book "Work Rules!," told Stephanie Ruhle in a panel interview at Bloomberg on Tuesday that most companies don't know how to hold onto their best people.

"People don't stay for the money," Bock said, noting that more than a third of Google's first 100 employees are still working at the company despite making boatloads of money in its IPO.

According to Bock, people stay for the following two reasons:

1. The quality of the people they work with

"That's why hiring is so important," he said. Google sets a high standard for everyone it hires. Whether you're applying for an administrative assistant position or that of senior engineer, every candidate is screened by their potential boss, potential colleagues, a hiring committee, and finally Google CEO Larry Page.

2. The feeling that the work they do is meaningful

"People want to do more than just make a buck," Bock said. "People want to do something that means something." Plus, giving employees a sense of purpose has benefits beyond retention. He cited research by Wharton professor Adam Grant that found when people are able to connect their jobs to something meaningful, their productivity increases as much as five times.

Interestingly, the lavish perks that Google is known for — free gourmet meals, in-house massages, and dry cleaning on campus — are nice-to-haves but ultimately not game-changers.

"The dirty secret of all these perks is it doesn't actually retain people or even attract people," Bock said. While the perks may provide efficiency, community, and an inviting atmosphere, he believes they ultimately won't swing people who are thinking about leaving.

Get the latest Google stock price here.

Read more: