The sport of diving started out as freediving, then later, SCUBA. Most of my generation and the one before started diving with goggles or mask and fins. The was no SCUBA instruction available but it really didn't matter. We were already divers and reading a pampflet "Diving with the Aqualung", was usually sufficient to get us started.
Only certain types of swimmers liked to swim underwater but those that did, once they put on one of the newfangled masks, often became hooked. They were also natural born hunters and this became apparent. Almost all divers then were soon spearfishermen. The conversion was spiritual and had to do with the love of the underwater world and the thrill of descending into the magic world. The mystical connection between the hunter and the hunted developed in subtle ways. It was very untechnical.
Because freediving is spiritual it is difficult to convey or explain. The selectivity is mental and depends greatly on your beginnings and expectations.
The tank diver or "bubble butt" as they are sometimes called, is most familiar with his natural sight picture which is primarily the bottom or elevated portions thereof. The freediver views the underwater scene from above and, diving, surveys the entire water column, repeatedly. Thus, the bottom dweller is more like a bear, snuffling, snorting and searching; a surface swimmer is more like a hawk, able to swoop down with virtual silence. If you really like the water, try freediving while cooking off. The tanker gets to spend a half hour on the bottom, returns to the boat, eats and sleeps. The freediver will often stay in the water for hours seeing all kinds of things the tanker missed and may never see in his lifetime. Mantas, mola mola, sharks, game fish, exotic invertebrates; literally all kinds of stuff. He can check the boat bottom and prop while he's at it(G).
Many freedivers, including myself, never really liked SCUBA diving. It was more of a tool or necessity for certain things. However, I have put in many hours on SCUBA, primarily wreck diving. I do enjoy that. Thirty years ago, my buds and I salvaged a Civil War wreck, a no no today. A few years later, I bought my own boat and returned to a mix of freediving and SCUBA. Some things, like spearing game fish, are best done freediving. I have speared game like tuna and king mackeral. Flounder hunting is mostly a SCUBA thing. For funsies on a slow day, we would salvage a boat load of lost fishing gear and anchors. Any excuse to go under.
I have trained a few SCUBA divers in reverse, so to speak, and taught them freediving. The ones that went on to become really expert in freediving and spearfishing were what I would call "outdoor" types, deer hunters and marksmen, one was a champion skeetshooter. The very best bluewater hunters that I have met could freedive to 80 feet, were deadly accurate killers, rugged individualists who yet had an undefinable spiritual quality, a real respect for conservation and the environment, almost fatalistic or mystical. Breath hold champions(there are many such contests) practice forms of self control that have aspects even I am not attuned to. Some freedivers look like athletes, some do not. However, the mental qualities are shared by most.
There are cultural aspects to diving. In Europe, especially Spain and Italy, record holding freedivers and champion spearfishermen are highly respected, even revered. The USA turned away from this for complex reasons which I can't go in to.
Later.