https://www.theguardian.com/technology/2018/apr/15/facebook-mark-zuckerberg-security-spending

In all the company has spent about $20m on security and private planes for Zuckerberg since 2015. The security funds were required ‘due to specific threats to his safety’

Facebook increased its spending on security for Mark Zuckerberg by 50% last year, the company has disclosed, paying more than $7.3m (£5.1m) to protect its top executive.