Washington's own bad news bear, Douglas Casey, is looking forward to 1981: he figures it'll be a terrible year for the economy.

Casey told you so, of course, in his best-selling book, Crisis Investing , that hit the nation's bestsellers lists this summer. ("It'll be the biggest book in 1980," he says, "bigger than Sagan and Ludlow and all those guys. Since July 7th, we've got 390,000 hardback copies in print.") Casey predicts the downfall of the nation's banks, the collapse of the real estate market and a depression by 1983, at the latest. Which means if you buy the doom-and-gloom preachings of Casey and others of his genre, you've got only a year or so to save your assets.

Between lecture dates and newsletter writing, Casey sat in his Beekman Place condominium (following his own advice, he only rents), and considered the immediate future.

"There's no such thing as investment now, only speculation," says Casey, "and what was speculative before is prudent now."

That's radical advice from the 34-year-old son of Eugene Casey, the largest single shareholder of the giant bank holding company, Financial General Bankshares, Inc. But it's a fitting statement from a person who likes to think he fashions his life in the style of Han Solo, the shoot-from-the-hip, man-without-a-country sky piolt in the movie "Star Wars." Casey is proud to say he hasn't received a dime from his wealthy family since he left Georgetown University in 1968. And if he followed his own advice of several years ago to invest heavily in gold and gold stocks, as he says he did, then he hasn't needed any outside help.

"I'd get out of the real estate market right now," counsels Casey. "Watch the bond market -- it'll be a good, short term speculation. In the next five years, the finest speculation will be penny mining shares that are sold in Spokane and Salt Lake City. The only money market funds you should be in are those that invest in the U.S. bond market.Watch the strategic metals, the war metals, such as cobalt and chromium, that come from unstable parts of the world."

"It's the world's unstability that Casey says fashions his strategy; he once told an interviewer, "I believe in buying when there's blood in the streets." And that's why Casey smiles smugly when he says, "I'll buy real estate in two or three years." And repeating something Casey says his father once said, "There's a time to buy and a time to sell."