Because the owners are not in it for the long term. It’s an agent problem - if they can take a company with a 2% profit margin and juice that up to 10%, they’ve captured 5 years worth of profits in a single year. If it takes 5 years for the market to catch on that the company’s gone to hell, that’s 25 years worth of profits available for stock buybacks-err, new investments. The company’s dead within a decade, but the owners and investors got a bucket full of cash.