Why do many businesses only pay careful attention to their Shareholders instead of their stakeholders?

Some consider needs of stakeholders irrelevant and often expensive to adress. They feel that improving the quality of employees lives is not the firms responsibility and unnecessary to spend money on e.g training and better conditions. They should try force the suppliers to cut prices in order to save money; pay as late as possible, to keep own money in bank for as long as possible. Firms needn't worry about the environment/ community unless law says to do so as any change in products process is an extra expense. Shareholders are the ones that actually invest money.