As gamblers, Tom and Philomena Drake of McMurray, Pa., have a lot to learn.

Last month, in a desperate bid to win that pot of gold at the end of the rainbow - $1,000 a week for life - the Drakes began to invest their life savings of $20,000 in the Pennsylvania lottery's Instant Bingo game.

At last report, having emptied their savings account and sold their car, the Drakes were still patiently scraping the film off $1 lottery tickets in search of the magic numbers or letters that would put them on easy street forever.

They would have done better to take off for Las Vegas instead. Casino roulette tables return up to 95 cents for the average dollar wagered. Slot machines spew back 75 to 95 cents. Illegal numbers games return 60 to 75 cents, horse-track betting 82 cents. But like most state lotteries, Pennsylvania's returns a paltry 45 cents. "No one but a fool would gamble with state-run operations," says Cornell Prof. G. Robert Blakey, who conducted a two-year lottery study for the Law Enforcement Assistance Administration. Consumer's Union concluded: Lotteries are "a legal sucker bet."

But even if the Drakes should beat the odds (35 million to 1 on each ticket, 1,700 to 1 on 20,000 tickets), does happiness await them? Many big-time lottery winners have succeeded only in screwing up their lives. Sociologist H. Roy Kaplan, who interviewed 34 of New Jersey's million-dollar winners, found disturbed relationships between winners and their families and friends, replete with jealous bidding for a piece of the winner's fortune.

Since New Hampshire introduced the first 20th-century state lottery in 1964, the games have spread constantly - now to 14 states - and have been "improved" regularly to bolster revenue and stop public interest from flagging.

But despite sharply increased gross revenues - estimates run as high as $1.5 billion for this year - lotteries remain one of the most oversold, misguided and morally reprehensible innovations in state policy in this century.

Lotteries are sold as a painless way for states to avoid new taxes, and most bettors believe that. In fiscal 1976 they did produce profits of $497 millin. But even that sum was only one-half of one per cent of the $104 billion it took to run state and local goverments in the lottery states.

Lotteries are highly inefficient revenue producers because prizes and administrative costs eat up 55 to 60 percent of gross. By contrast, it costs less than 5 cents on the dollar to collect most taxes. The lottery states could recover far more through pared-down bureaucracies and more progressive tax systems.

Lottery boosters claim that their games compete with illegal gambling and thus impair organized crime. It's hard to find a law-enforcement officer who agrees.

Says Jonathan L. Goldsten, U.S. attorney in New Jersey and one of the nation's top crime fighters: "The state lotteries make gambling respectable and thus create new clienteles for organized crime to prey upon. You become addicted to a lottery system." From there, Goldstein says, it's a short step to illegal gambling.

Goldstein's charge of a tie between lotteries and criminal activity was supported by the National Gambling Commission's findings that lotteries tend to increase participation in illegal numbers games, and that participation in illegal gambling is more frequent in states with legal gambling than in those that prohibit it.

So far, the modern lotteries have escaped the gross corruption that wracked their 19th-century predecessors. But the aroma of scandal - real or potential - is already evident in heavy patronage staffing of some lottery commisions, political influence in doling out highly profitable lottery outlets, irregular expense accounts, awarding of lucrative consultative and promotional contracts, and the gangland-style slaying of New York's leading owner of lottery ticket vending machines.

Proponents argue that lotteries are a voluntary, harmless form of entertainment, overwhelmingly backed by citizens in referenda. The gambling commission found 61 per cent of the public favored lotteries.

In the Norhteast, an astounding 84 per cent were in favor. Yet it was a New Englander, Ralph Waldo Emerson, who urged there always be "a minority unconvinced." And so it is on the lottery issue. Critics question whether "making book" - enticing citzens into gambling with such slogans as "Play Me," "Diamond Dollars" and "50 cents can make you a million" - is a proper function of goverment.

The promotional advantage is all with lottery proponents (except in the South, where religious opposition remains strong). Accentuating the riches to be won, state lottery advertisements now appear legally on television and accost the consumer in at least 70,000 ticket outlets, from drug stores to supermarkets. Lottery tickets, the gambling commission observed, "are in the unique position of being the only consumer product that is widely advertised and backed by the prestige and integrity of state government."

Legal lotteries, U.S. Attorney Goldstein observed, "begin to blur people's ethical and more values. It's a very grave error for states to participate and keep on promoting them."

Be that as it may, the tawdry spectacle goverment as bookie seems likely to expand as politicans - reacting to public pressure - seek an escape from new or higher taxes. Patronage appointess, state lottery bureaucracies, vendors and consultants will provide political muscle and needed cash in political battles. Only a chain of horrendous scandals killed off the state lotteries of the 19th century. It will probably require the same in ours.