Yes, i have seen and handled classified material--top secret and others.  As many of you may already know, i served as a junior officer of one of the U.S. fleet ballistic missiles submarines for four-years.  Essentially everything we touched and saw regarding the nuclear ballistic missile submarine was classified at least in some manner.  That typically was not an issue since most of the time we handled this information we were already in a secure environment (e.g., the submarine itself, the Navy base buildings when off-crew). 

In the Navy i had a Top Secret clearance.  Probably for good reason because each of the sixteen missiles we carried held ten nuclear warheads each--for a total of 160 warheads in all.  All of our operations (location, depth, speed, etc.) were classified and much of that was Top Secret.  In Norfolk at the office of the Commander of the Atlantic Fleet we were taken into a secure room that was inside another secure room and shown some very interesting things regarding the Atlantic Fleet and other Navys of the world...

As a civilian i also handled classified material.  At the Department of Energy i had a "Q" clearance.  A Q Clearance is equivalent to a U.S. Department of Defense Top Secret clearance. "...the Q access authorization corresponds to the background investigation and administrative determination similar to what is completed by other agencies for a Top Secret National Security Information access clearance." 

The Department of Energy came into being from the Manhattan Project, then the Atomic Energy Commission, then the Energy Research and Development Department, and finally the Department of Energy.  The Department of Energy is essentially the government agency (department) responsible for nuclear weapon research and development managing national laboratories such as Los Alamos, Oak Ridge, Lawrence Livermore, etc.

Handling even "confidential" classified material is a pain.  Like i said before, in the Navy it was typically not much of a problem because of our secure environment.  That is different in a less secure area.  In one job where i handled classified information every time i went to the "head", i would have to take the material i was looking at at my desk and put it away in a safe before i could take a piss, then retrieve it again when i returned from the john..

Believe it or not, most people i knew hated to handle classified material.  There is no big rush in seeing classified material.  You cannot talk about it.  You cannot take it home with you.  You cannot do anything with classified material other than see it, read it, or hear it--and that is all.  

And no one in his/her right mind would take "classified" material home with them.  No one in their right mind would even try to sneak it out of his/her workplace.  Why would one?   If i had done so, and anyone else knew about it, i would have been in deep shit--and i mean really deep shit.

Taking "classified" materials home by mistake can hardly be used as an excuse.  No one can claim that.

There are different levels of even the most sensitive classified material.  For example, the captain of our submarine saw "classified" material that was for his eyes only--none of the rest of us on the submarine could see it.  So, you can imagine the type of "classified" material a President of the United States may see.  The President of the United States sees things for his/her eyes only that a captain of a fleet ballistic missile submarine would (nor should) ever see.

There is nothing good you can do with classified material other than store it in your brain someplace--and then to try and forget about it once your need to know is no longer necessary.  It has yet to be shown and/or proved that President Trump (i always a hate to use that term) mishandled classified material, but my bet is that he did.  And it will be my belief that he did so "knowingly".

The big question is:  Why?   Why would an ex-President want to hold onto classified nuclear weapons material?  What good would it do him or her?

So before you start calling for the overthrow of the Department of Justice and the Federal Bureau of Investigation, you might just want to ask yourself several questions.  Do you really want "nuclear weapon classified" material lying around outside a secure environment?  Do you think the Government has the right to protect sensitive "nuclear weapon classified" material?  

You might even ask, knowing about our ex-President's seemingly close ties with Vladmir Putin, what did our ex-President want to do with the "classified" material that he was previously unwilling to turnover?  Did our ex-President have our country's best interest in mind?

I do not really care how you answer the above questions, but based upon my experience and knowledge, I am glad the FBI (and Justice Department) took the somewhat unobtrusive steps they did this past Monday.