The made so much effort not to get caught. Secret signs, costumes, fake IDs, the whole role playing routine, and yet they made the biggest mistake you can POSSIBLY do: winning, winning, winning, winning and winning without end. Why were they so stupid?
shareNobody?
shareWell yeah, true.
Because at least in prison and at least in death, you know, I wouldn't be in *beep* Bruges.
They decided to tight instead of loosing.
shareThey probably did lose every now and then. It just wasn't shown.
shareThey certainly lost. And lost often. Even with counting they still would only win maybe 55% of the time tops. So even to win just 10 more times than you lost you'd need to play 100 times. That's why it cost so much to play.
shareEven with a good card counting system, going to Vegas a few weekends a year won't make you millions in the way it was portrayed in the movie. You will also lose heavily. If thanks to your card counting system you have a slight edge over the casino, chances are you will be up over the long-term but, in between, there will be a huge variance.
shareTheSummer and uno are both correct.
They had a small edge, meaning that they needed to have a large amount of cash to win. They might be expected to win 10% more than they lost, so that the profit was expected to be 50k on 500k. That is why they needed to be bankrolled, they had slim margins. Some weekends they did indeed lose, they were just trying to bet so often that they would win in the long run.
If you read the book, it is explained in more detail. I encourage everyone here to read it, as it is spectacular. It takes them several years to get caught.
Mezrich's book "Busting Vegas" follows a team which used card sequencing and card steering, which were much more powerful techniques. That team made money much more quickly, but was also caught more quickly. I think that book is actually the better of the two, and would have made a great movie. It is an absolutely riveting read.
They did lose. Remember the scene where he said, "I guess tonight is just not my night."
shareOn that occasion though I am sure Ben was gambling rather than counting.
shareEven before he broke from the system and started gambling, he was already losing that night though - that's why he lost control - was betting big trying to chase the losses.
Sometimes you'll still get unlucky (see also Jill Taylor's story on the subway of the dealer making 21 against all odds and her dad losing a ton of money because of it)
I think this is illustrated in the scene where Kianna says (after Mickey bails) 'and what, play with our own money?' - maybe he had some sort of fund set up that could take the immediate hits while they were still up overall. With their own money though, they knew they were at risk of losing what they'd won thus far.
'I just wish, for once, people wouldnt act like the *beep* clichés that they are' - Claire Fisher
How often were they going to Vegas?
It sure would have helped them get away with their scam if they played in different casinos and/or cities.
Why didn't they loosen what?
shareIt seems that in order to "cover their tracks" they should have lost every now and then. But as others have already explained they were only winning slightly more than average with their method, not every hand like it was glimmered up in the movie to be. Unless you mean winning overall on the night every time. To lose purposely on the whole night would eat into their winnings and might not have been deemed worth it in the long run. To lose money in order to cover their tracks slightly better just wasn't worth it in their minds I guess.
What they SHOULD have done is not visited the same casinos and got to know the dealers by name (the dealers would notice they would win overall every time quicker than the eye in the sky would, though they seemed more intent on fooling the eye in the sky). They should have mixed it up and gone to Atlantic City or some other underground casinos just one time. It would seem easier to fool 10 different casinos once than fool the same casino ten times, no?
Edit to Add: To temper what I just said, I guess the underground casinos didn't have much capital to work off of to make it worth it. As previous posters have said, they would only win maybe 10%. So to make it worth it they would have to gamble 500K and underground casinos usually aren't equipped to handle that kind of capital. They still should have tried Atlantic City every once in a while. Atlantic City approved gambling in 1976 and the scheme the movie is based off of ran from 1975 to around 1990. It seems that the team as portrayed in the movie got lazy after a while and stopped using aliases and disguises. And when they got to know the dealers and became regulars of them, it would have made sense to lose on the night every once in a while as pointed out by the OP.