Of people who call themselves card counters, yes, sadly I do believe that. I've taught dozens of counters, and maybe one of them had a "winning game" albeit rough understandings of RoR/Kelly/etc. And of those people I've taught most came from one forums or another where they'd already been exposed to these concepts, let alone the random friend/family/etc... And I've run in to other "counters" at the tables and in convo they show they don't know these other things at allllllll.
I seriously think the casino should do this: You're allowed to card count if you spread 1-100. 99.9999999999% of people won't have ANY concept or RoR/Kelly and they will go broke even if they count PERFECTLY and play PERFECT deviations just because they don't understand those core concepts. Never mind that the true professionals (1% of 1%) would have a field day... the others would lose more than they would make due to the shier number of losing counters.