Well, I spend more of my time playing against players now than the casinos, so one of the full-time votes may, or may not, be valid.
As for the weekend warriors and counting, I'm not really a big fan of the concept. Many will never play long enough to overcome a bad stretch of variance, so I consider most recreational counters to be engaged more in gambling than advantage play.
Mind you, I have a somewhat more personal definition of 'advantage play' than most. In brief, simply having expectation on a given play does not meet my needs. I've probably been most influenced by poker in this regard, where I routinely pass up slight edges for locks. There is some debate on this, even in the poker community, but little to none from those who play for a living.
You can pick your moments.
And KJ, don't cut yourself short. Most people who play part-time would be incapable of playing full-time. At least, not with the slight edges a typical weekend warrior has with counting. One of the reasons that most successful full-time players abandon counting is that THEY can't handle the fluctuations. It is out of the need for brute survival that they gravitate to stronger methods. Methods that are out of reach for the recreational player.
This is a bit of a sore point for those who make advantage play a significant part of their recreation, but do not derive the majority of their income from it. Simply having the attributes does not make you a contender. And you simply don't know how you'll react until your livelihood is on the table. It's more an issue of intestinal fortitude than intellectual prowess. I'm certain, for instance, that a QFIT has a far stronger grasp on the mathematics of advantage play than myself (at least, I would certainly hope so!), however ... I am also certain he would never place himself in the situations that have been instrumental in my growth as a player.
So, yes, in a way some could be more successful as full-time advantage players ... but they never will be. Nor should they even attempt such folly. It's not in their nature, and this isn't a bad thing.
Best,
Syph