We have three levels of network connection:
1 the main network (wired and wireless), which is monitored and has severe restrictions and is there for work purposes only
2 the secondary network (again wired and wireless), which is monitored, but has very few restrictions and is there for visitors, clients, and others. Just don't attach a company machine unless you've got permission in writing. The secondary network is _NOT_ connected to the main network.
3 whatever you have attached to your own devices. If you _don't_ want to be monitored, then bring your own connection. Problem done. (Just don't attach that connection to a company machine unless you have permission in writing...)
The company does not care what sites anyone, including staff, goes to if they're using their own stuff; your own security is your problem. The company cares deeply about not getting malware on the main network. It cares deeply about maintaining system integrity. It cares deeply about data security. Anyone who exposes the company's main network to a problem will be fired, forthwith. It will not matter if no problem resulted. All that will matter is that the idiot in question deliberately tried to circumvent system security.
There are alternatives to using the main network for visiting Arsebook, and the company actively encourages staff to use those. And, should you really, really, REALLY need to get to some site on the blocked list for a legitimate reason, the block can be overridden just for you and just that one time. (And, yes, the logs will show who overrode the block so there had better be permission for said override, in writing.) Should some twat evade the blocks and use the main network and we find out about it (and we _will_ find out about it) we will drop the hammer on said assclown. There have been, in the past, clever dicks who thought that they were smarter than we are; they are no longer employed here.
This is a place of work, not a playground. If someone uses company equipment in ways contrary to their terms of employment (and everyone signs the Internet and Computer Usage Policy documents as a condition of employment and is issued with their very own copies of our policy book) then they will no longer be employed here. They can then go and hang out on Arsebook or whereever to their heart's content.