In Treasure Island, why don't Jim and his mother grab the money the captain owes them and run from the inn?
"The captain" is Billy Bones, a grizzled and unpleasant sailor who stays at the inn for months, falling far behind on payments for his boarding, and at this point in the story, has just died of alcoholism immediately after being marked for death by his former shipmates.
Bones arrived at the inn with a "sea chest", or footlocker, that he seemed to keep well-guarded at all times. Jim and his mother suspect he keeps some kind of treasure in it, at least enough to pay his debts, and they decide to open it before the other pirates arrive, confident the pirates will fail to pay the dead man's debts, let alone spare Jim and his mother. When they open the chest and find Bones's store of gold, Jim is inclined to simply take all of it, but his mother insists on only taking the amount she thinks Bones would have owed them. She does this as a matter of pride and moderation, since no one but she and Jim would know the better.
The pirates arrive earlier than expected, and Jim, wanting to "even the score," so to speak, takes what turns out to be the map to Treasure Island, since they didn't have enough time to count out the money Bones owed.