The article discusses how a company needs to make sure its investments bring in more money than the cost of getting that money. The cost of getting money isn't easy to figure out and needs assumptions about how people spend, save, and invest. The article looks at different studies on how companies figure out their cost of getting money, like how much it costs to borrow or how much investors expect to make. It also talks about different ways companies can calculate this cost and why they use those methods.