As long as you realize your gains before the stock tanks, why do you give a fuck? The only people affected are the employees, the customers, and the mugs who invest for the long term.
If you expect to make your gains on the stock price (not, say, dividends), it's a perfectly rational strategy. Of course, it leads to things like IBM borrowing money for stock buy-backs to pump the price to make the numbers, which will be a long term disaster...