IT'LL cost you $18 an hour to gamble in Atlantic City. if you're the average betor. So says a report from Associated Press.

This is one reason the casino business is very, very hot right now.

In a few years, you may be able to risk your money in casinos in Miami Beach, Pennsylvania, New York, Michigan, Washington state or California, says Duane Burke, head of the Public Gaming Research Institute in Rockville.

And don't count out Ocean City. City and state officials may be against it, "but it would probably take only one bad summer, along with the success of Atlantic City," Burke says.

Right now, 31 states let you gamble on horses; 14 states have lotteries; seven allow dog racing; four have jai alai; two have casinos, according to Burke. You'd have to look hard through all 50 states to find one that doesn't feature varying illegalities of numbers games, bingo, punchboards, football pools, poker games, raffles, wheels of fortune, back-alley crap games, blackjack, even roulette or baccarat if you know the right people.

Virginia, with its dreadnought cops busting bingo games right and left, is a nice place to put down a bet in public almost any time the point-to-point races are being run. The law doesn't hit those blackboard bookies very often, but then, the odds offered are punishment in themselves. Now, Virginia is going to let the people decide on pari-mutuel horse betting in a a referendum.

Guiding lights among us complain that gambling is a tax on the poor, a regressive tax, and an infernal temptation. They neglect surveys which show, for instance, that 75 percent of Democrats in Ward 8 (Anacostia) want legalized gambling, while only 34 percent of Ward 3, in palmiest Northwest, approve of it.

But, like gamblers, legislators like the prospect of easy money, so they legalize wagering in the form of, say, a lottery like Pennsylvania's, which returns you only 45 cents on the dollar, as opposed to more than 95 cents in a good crap table bet in a casino.

Maryland has its horses, its lottery and its numbers game, which is equipped with a computer to curb superstition. Last year, for instance, on July 7, 1977, which is 7/7/77, the computer had to turn away bets on seven, for fear they'd win and bust the bank. (They didn't.) Maryland once had slot machines, which Marylanders talk about with nostalgic reverence. Nobody ever believed they'd stay illegal when they went, and so stories tell of warehouses full of the machines, waiting for The Day.

People get so worked up. The Protestants say it's a moral issue, the Catholics say it isn't. Everybody worries about the Mafia moving in. But the real muscle is being flexed by corporations that trade on the New York Stock Exchange, because "gambling is on a read-hot growth streak," says Forbes magazine.

In Las Vegas, the big winner in MGM, whose Grand Hotel cost only $124 million to open, and brings in $11 million operating net every three months. The worst performer in Las Vegas last year, among those that report to the Securities and Exchange Commission, was the Dunes Hotel, with an operating net of only 5.5 percent - about the level of the rest of American business.

So if the tales you're about to read imply that there's something cool and calculating about Atlantic City, there's good reason. And a moral to be learned: You want to make money in a casino? Own one.