The prophets of gloom and doom; Crisis Investing: Opportunities and Profits in the Coming Great Depression, by Douglas R. Casey. New York: Stratford Press (distributed by Harper & Row). $12 .50.; The Coming Currency Collapse, and What You Can Do About It, by Jerome F. Smith. New York: Books in Focus. $12.95.

Tremble in your boots, dear reader. If you were to believe these two books -- Nos. 1 and 5 on the New York Times list of best sellers -- the economic scene is gloomy indeed: Ahead is currency collapse, hyperinflation, and depression.

Of course, with prevailing double-digit inflation and stratospheric interest rates, the financial world is troubled, and people have some justification for being concerned. But these are the kinds of alarmist outcries that would have impressionable readers pulling blankets over their heads. The authors overdo legitimate concern.

It is difficult to tell whether Casey and Smith are genuinely alarmed or whether they are exploiting today's hot market for financial doomsday theories, vented in various books, investment seminars, and stock market letters.

The basic premise of these books -- that inflation will worsen until the economy buckles -- seems highly unlikely. Both authors appear superconfident about their own views and willing to assume that government officials and politicians are incapable of learning from their mistakes. The writers maintain that the Federal Reserve System will continue to increase the nation's money supply at ever faster rates until the dollar is worthless as anything but wallpaper.

But in this reviewer's opinion, that is not the case. Fed officials and government economists are neither stupid nor incapable of improved judgment.

The evidence is mounting these days that the Federal Reserve System, now backed by a Republican administration, is bringing the money supply under better control. And even before the new administration there were signs of improvement. The rate of growth for one measure of the money supply, known as M-1B, was 8.2 percent in 1978, 7.7 percent in 1979, and about 6.3 percent in 1980. That is far higher than rates that prevailed in the relatively noninflationary 1950s. But the trend is downward, and the growth is not rapid enough to support hyperinflation. In fact, inflation could turn sharply downward next year. So the basic thesis of the books is wrong.

The '80s may well be economically troubled in various ways. But that does not mean catastrophe ahead.

What gives these authors considerable credibility, however, is that they are members of that circle of "gold bugs," silver enthusiasts, and adherents to the Austrian school of economics who have correctly warned that major federal budget deficits, combined with the printing of too much currency, will lead to the debasement of the dollar -- to high inflation rates and increasing prices for precious metals.

The dust jacket of the Smith book, for instance, claims that his newsletter, World Market Perspective, advised subscribers to buy silver, gold, and platinum just before major price increases. (Both authors plug their own investment letters in these books.) It is certainly true that during the 1970s the gold bugs were in their glory, but will that be the case in the '80s?

If the Federal Reserve finally does minimize money-growth rates and thus bring inflation under better control, it may well be that some of the investment advice in these books will prove less sound than if the economy soared into gross inflation and collapse. It could well be, for instance, that stocks will do better in the '80s than precious metals or diamonds. Time will tell. If so, the authors' careful note of the corrosive effect of inflation on many investments will not apply.

Another warning about these books: The authors are supercapitalists. Casey gives us a corny allegory about a utopia where private enterprise carries out many of the activities of today's governments. And Smith favors a libertarian position which would dissolve public authority.

Perhaps it could be said that these books offer a useful warning about the financial chaos that could be caused by incredibly irresponsible government officials. Both books, however, strike me as akin to horror movies -- using fantasy to make things scarier.