bigplayer had it right
There are many pro individuals playing to banks well into 6 figures or more, and a few teams with members playing to a bank well into 7 figures. Although agreed it is a finite number, I wouldn't call it an "elite" group, and the number is growing. Many of these people have been consistantly taking 6 figures a year from the casinos for years even with current heat conditions. Imagine what would happen if the casinos turn us loose. Spreads widen, cover costs vanish, bankrolls grow rapidly, teams recruit & train more members, more individuals hear of the opportunity and learn counting. The casinos would be crushed in a relatively short time.
Just as in any business in life, if there is an extremely good opportunity, there will be many to jump on it. If a so-so opportunity is available, fewer people will go for it. The casino must offer just enough heat, poor pen, poor rules, etc. so that the opportunity is not good enough to encourage the masses to learn counting and quit their day jobs, but good enough conditions to attract the ploppies.
You have to look at the playing conditions that would exist if the environment was changed to no heat, and realize that it wouldn't remain the same. As examples, there have been several cases of casinos offering a too generous promotion. Counters would flock to the game & burn it out in a matter of hours. The promotion intended to last all day or maybe a few days would be canceled as the casino quickly sees it's losses on the promotion mount.