So would everyone that ever created a business. Nobody grows headcount if they don't have to. Why be responsible for other people's livelihoods if you can make it work with less people? Just more worries and responsibilities.
From my experience in corporations this is a false statement. The goal of each manager is to grow their headcount. More people under you - more weight you have and higher position you got.
Because he is the fourth richest man on the planet and that demands some responsibility, which he refuses to take.
He owns 162,000,000,000 dollars. Metas net income 2024 was 50,000,000,000 dollars.
Facebook might be able to operate with half the headcount, but them Zuckerberg wouldn't be the boss of as many people, and I think he likes being the boss.
If you had hired people (and been responsible for their salaries and benefits and HR issues), you would definitely not say that.