Facebook users are "finally starting to recognize that this is not the fun and games, innocent place they thought it was," tech investor Roger McNamee said Monday.
The social media giant is coming off a rough weekend, after reports late Friday of a massive mishandling of data by conservative research firm Cambridge Analytica — data that it got from Facebook. The news resulted in the social network's stock shedding more than 7 percent Monday
But the greater loss may be the trust of Facebook users, McNamee, co-founder of investment firm Elevation Partners, told CNBC's "Squawk Alley."
"There's been an increasing understanding that when you're using Facebook, a lot of bad things are going to happen to you, as a user," McNamee said. "That is not a 100 percent guarantee, but the risk is really, really high."
It's not the first time Facebook has battled issues of user trust. The company has been facing increasing pressure from tech insiders and lawmakers to give greater transparency into its data and advertising businesses — particularly after the discovery of Russian meddling on the platform during the 2016 presidential election.
But it is one of the first instances of consumer sentiment so significantly hurting the stock. The stock's Monday plunge is the company's biggest single-day drop since September 2012.
"In my mind, trust is the thing that makes these [internet platforms] successful," McNamee said. "I am an investor. I want them to have the trust of the users."