It bears no relation to the risk of revenue loss for the airline. It is based on demand. An airline runs hundreds of flights a day, and it knows that a certain percentage are going to be less than full. It tries to optimize as best it can. You on the other hand are going to be seriously annoyed if you have to change your plans and you lose hundreds of dollars, maybe a significant proportion of the money you have for your trip. They are going to charge you based on the price you're willing to pay for peace of mind, far lower than the cost to them. After all, most people do use the plane tickets they have booked.

The solution is to self-insure by having $1000, or whatever, ready for if you need it for increased travel costs or other emergencies. And try to avoid feeling either anger or regret if you have to change your plans. If you don't have a spare few hundred bucks then this method isn't available to you.