Sam Ace Rothstein is the best 'professional gambler' in the movies though ;-)
Kinda an idol of mine in a silly way:

NICKY: (Voice-over) And that's how that got Ace to take over.
(ACES's hands place the die into a micrometer.)
They wanted him because Ace ate, slept and breathed gambling.
(Camera swish tilts up to ACE, then swish pans to boxman, dealers
and players watching him, trying to act calm.)
They worked out a real cute job title too.
(We see the die in the micrometer.)
Tangiers Public Relations Director.
(Satisfied the die is not loaded ACE sets it on the craps table,
the camera cranes up to reveal the Tangiers Casino floor.)
But the only thing he ever directed was the casino. He made his
first bet when he was fifteen years old, and he always made
money. But he didn't bet like you or me.
(A DEALER is sliding ***** tossing them on to a craps table.)
You know, havin' some fun with it, ** like that.

ACE: (Approaching the DEALER) Where the hell did you learn how to
deal? (He reaches down, stacking and arranging the *****)

NICKY: (Voice-over) He bet like a **in' brain surgeon.

ACE: (To the chastised DEALER) Place the checks properly. That's
the way you do it.
DEALER: Yes, sir.

NICKY: (Voice-over) He had to know everything, this guy.
(Direct overhead tracking shot as ACE walks between two rows of
gaming tables.)
He'd find out the kind of inside stuff nobody else knew, and
that's what he'd put his money on.

INT. GYM/BOOKIE JOINT, BACK HOME, PRE-SEVENTIES - DAY

ACE walks past two boxers sparring in a ring, through a doorway into a room
where several gamblers are seated around a table.

NICKY: (Voice-over) Even back home, years ago, when we were first
hangin' out together . . .

TITLE IN: 'BACK HOME, YEARS AGO'

. . . he'd know if the quarterback was on coke.
(ACE is looking at the odds board for college football games. The
bookie, LUCKY LARRY, is waiting for ACE to hand in his picks.)

ACE: I'll take Columbia for twenty.

NICKY: (Voice-over) If his girlfriend was knocked up.

LUCKY LARRY: Twenty dimes on Columbia . . .
(As soon as ACE bets, a man erases a number from the chalkboard
and replaces it was a '6', changing the odds. Two GAMBLERS
saunter from the room.)

NICKY: (Voice-over) He'd get the wind velocity so he could judge
the field goals. He even figured out the different bounce you got
off the different kinds of wood they used on college basketball
courts, you know?

EXT. GYM/BOOKIE JOINT PUBLIC PHONES - DAY

The two GAMBLERS we saw sauntering out of the bookie joint are racing to
the nearest public phones. Another GAMBLER has already beaten them to it.

NICKY: (Voice-over) He'd be workin' on this ** day and night.
There was nothin' about a game he was gonna bet that he didn't
know.

GAMBLER #1: (Into phone) Ace got down at six.
GAMBLER #2: (Into phone) Charlie, hey. Rothstein got six.

INT. GYM/BOOKIE JOINT, SEVERAL DAYS LATER - DAY

A bookie hands a stack of money to another bookie, who hands the money to
ACE. ACE removes several bills from the top of the stack of winnings and
holds them out to the BOOKIES.

NICKY: (Voice-over) Season after season, the** was the only
guaranteed winner I ever knew. But he was so serious about it all
that I don't think he ever enjoyed himself. But . . .
(Ace exits.)
. . . that's just the way he was.

how did casino take so long to get a mention?

The Sting is the classiest and best by a long chalk.

The Gambler is absolutely brilliant!

Is that based on Dosteovsky's book?

Not really, though it may well claim to be.

There was a BBC film in 1990 called 'One Last Chance' that was quite good.

the hustler is one of the best films, full stop!

Man With The Golden Arm?

Cool Hand Luke

a very good shout speedypro, had forgotten that :)

Croupier aint bad either, really captures the late-night feel of gambling lifestyle (even though a croupier, so not strictly a 'gambling' film?)