I don't think you mean this. Surely what you mean is that the market capitalisation of United went down by $2.5bn. That is quite different and far less serious for the business. What may hurt them is lost sales due to poor brand image. As others have pointed out, image factors like quality of customer care are only a minor factor in most consumers' buying decision for air travel, price being a lot more important. But brand image is still a factor and may have some impact, where the customer has a number of choices that are close in price. This would be magnified if other airlines seize on this as a chance to differentiate themselves by not treating customers like dirt. But again, that may only have a small effect compared to price. If they started crashing planes, now that would different.