Guests at nearby lodging houses pay $2,000 a night for a room, and a well-known and popular activity is for them to take food from the lavish buffets down to the water's edge and throw it into the lagoon for the alligators to eat. There are signs that say Do Not Feed the Wildlife (it disrupts their natural habitat, it's unsafe for the animals, etc.), but not a word of how it can become dangerous for humans.
Disney freely admits they have an ongoing program to remove gators that have grown to longer than 4 feet, because they can be a hazard for the guests. The one that struck this week was estimated to be 7' long.
This was a problem waiting to happen. No surprise. Disney is going to pay for this mistake.