“Gross weight still is weight. “
Well, it is and it isn’t. Weight or pressure per a given unit is what determines stress levels. I’m trying to think of a good example for you. How about an Abrams tank; it’s weight I’d distributed across a large tracked surface which reduces its weight per surface unit over other drive systems which would not be capable of supporting it on the surface of sand, mud, etc. a good source that you may find helpful is the wikipedia site for the B-36. The B-36 had to deal with this exact problem. The plane first only had one huge wheel per side. The concrete literally crumbled under so much pressure applied to such a small area. The problem was solved by installing what is referred to in the aircraft business as “trucks” of four wheels per side.
Concerning where the 777 may be; odds are in your favor that it is indeed a submarine. But, that’s no fun, my theory keeps the intrigue alive :)
That theory won’t get airborne. I’ll grant that you could get it on the ground, just don’t buy the surface holding up for a takeoff with useful load.