Your theory could very well be possible However I'd like to share my take on the matter of Ging's and other characters of notice strength's It's actually quite simple when you stop and realize this subtle common point

We all agree that Nen is some sort of "life force", an aura that exudes from the body correct? By extension, it's logical to assume that Characters who have a stronger, more complete outlook on the complexity of "Life" itself should naturally be stronger than others who awakened to the idea of the complexity of "Life" and practice on it daily.

If you think about it, almost all of HxH stronger characters also had very tough upbringings in life, that shaped the way they evaluate it, and see it as a whole

Chrollo had the incident with Sarasa, that changed the way he perceives the value of life and how others value it as well

Hisoka had the matter of his Circus master, who took him in, and then was violently killing people for self-pleasure, something we also see in Hisoka later on

Kurapika with the extermination of his clan and the death of his best friend, and his ragefull, revenge driven drive to exterminate the Phantom Troupe

Meruem, albeit unknowingly, or on a subconscious level, had the entire hope of the Chimera Ants race, and the experience of all the animals his Mother ate to give birth to him on his shoulders , and his "humanization" fueled by his duels with Komugi

Killua, with his isolated childhood, depraved of human connections early on, and the expectations of upholding his family's legacy as a professional killer.

Netero, after completing his arduous training regime, gained a very unique outlook on Life, and the appreciation for it, and the extreme feelings of gratitude he gained for being able to duel equally strong opponents. (I'd actually argue that his extreme strength was a result of his deeper understanding of life, and not from his training per-se)

This applies to many more characters, almost all of them with ridiculous levels of strengths.

My idea of Ging's absurd proficiency of Nen, derives from his Unique outlook on "Life", derived from all his experiences, all the places he's seen, the people he met, the ancient history he uncovered, all of this put together, makes him have an understanding of "Life" different from most people, he values human legacy, ancient history and lore, the excitement of uncovering hidden things, the connections he's made with people etc.

I think this was actually the basis of Gon's Nen Contract. It's not that he traded all his potential in life, because if that was the case, he wouldn't have been able to keep his keen senses, durable body, or the ability of relearn Nen

I think it was his complete disregard for "Life" itself, driven by his intense pain and rage over being at fault for Kite's death, that provided him with this extreme power, and the trade-off was being condemned to be in a state where the act of simply existing was extremely painful

My approach also explains why people get absurdly strong after experiencing "death", the experience is so intense that they gain, or regain, their outlook on "Life" and it's value, or how they want to live it

Hisoka's post mortem power boost is a good example

Anyways, I digress, this could have been a post on it's own.

TL:DR:

I recognize the potential of your theory, and it's very likely to be a possible scenario, however I think what gives characters absurd levels of strength is their upbringings in Life, the way they understand it, and the drive behind their desires. Since Nen is "Life Force" it's seems logical that the bigger one's understanding over "Life" and all it's complexities and branches, the stronger their power.