Try how much ever you want, try any technology or software, but you just can’t block the Facebook CEO, Mark Zuckerberg. He has always been the ‘unblockable Zuckerberg’ for years.
According to Mashable, it's the product of a safeguard built in to the site to prevent trolling campaigns against certain people.
If one account has been blocked a lot in a short space of time, the safeguard will kick in and prevent any more blocks, just in case the person is being targeted by bullies or a viral campaign.
Facebook says the system is there to "protect the experience for people targeted by these campaigns."
So there's no foul play going on, it's just an automatic block-blocker.
So indirectly it is so evident, that lot of people round the world are trying to block Mark Zuckerberg. He has got over 40 million followers.