Yes, you,
personally have an incentive to be stingy.
But when you are talking about a big organization, they find ways of spending money because the managers of the organization are not aligned with the shareholders. Every organization has pressure to keep expanding because there is always more stuff that could be done, and you can hire people to do that stuff up until the total earnings are in line with the market return irrespective of the above average earnings that could be had without all the extra activity. They will keep spending on marginal expenses to "defend" their rents up until no rents are to be had. This is called rent dissipation.
A good example would be education, and count the number of educational administrators, gold plated dorm rooms, activity centers, weird classes, etc. Then go look at hospital spending. Instead of the nurse giving you a tylenol, they invest in a prescription dispensing vending machine that costs $$$, and they hire more administrators. Then take a look at your standard corporation and look at all the odd positions they have that a "lean" smaller company or a start up would never have. Compliance officers, marketing staff, assistant to the marketing staff, support services, travel support, real estate management services, etc.
So you can think of this as a law of bureaucracy, unless there is someone imposing discipline on the cost side, the managers of a bureaucracy are going to grow that bureaucracy until they run out of money. This is how ATT ends up funding basic research and discovering the cosmic microwave background radiation. Because they have all this money to spend. And I guarantee you that at its halcyon days when it was obviously a monopoly and thus earning monopoly rents, ATT was not earning more than the average market return on their investment because they kept "investing" in hiring more staff and more resources up until the total return fell to the market required return.