Their is a surprising number of folks who will try SCUBA and then decide it's not for them. This obviously doesn't include the folks for which fear of drowning is a consideration. For others they absolutely love SCUBA and will use any opportunity to get some time underwater. As with the paratroopers fear of heights and being a paratrooper is somewhat mutually exclusive. I guess the same applies to those who see themselves as a Navy SEAL. I suspect that there are probably some who actually miss the opportunity to get more pool time during the BUDs course (they love the buzz/fun it gives them)
I don't know. I think we're talking about different things here. I'm a good swimmer. I can also swim back and forth submerged on a fairly long pool. I don't normally have a fear of drowning. However, if I were to swim the length of a pool submerged and then unexpectedly have someone force me to stay down there, I would suddenly have a fear of drowning at that moment, even if I could have easily stayed down there another 30 seconds on my own will. The fear at that moment would likely be greater than any other type of fear I have. I'd consider the fear of being buried alive to be about the same.
Anyway, it's all talk here, unless you or I have actually been through the Navy SEAL pool competency test.