It may have been a rash decision but it was hardly peanuts. The cost of that bus service was a lot more than most of you can even imagine. You tend to think of it as the same as driving a car to and from the airport. It is not. It involves running buses all day long back and forth between the resort and the airport. And not just one bus, but at least 3 (probably more) along with pay for the drivers, fuel, insurance, maintenance and repairs. They were paying a third party to supply all that stuff, the buses and the rest of the expense and that third party has to make a profit on top of that. It is millions/millions of dollars per year, just for the buses alone. It was to keep people on the site but with the addition of Uber and Lyft it no longer was working to their advantage to make the cost worth the return. People got to the parks for 30+ years before the Magic Bus existed, they can do it again.
The profit was always at the expense of the guest, otherwise admission would be free. It's just that Disney got unusually greedy and they will eventually pay for that greed, if they aren't already.