It's the training data. Every list the bot has ever seen has had the number 1 in it. All other numbers come up less than that.
The bot also has no memory of what it wrote before, and no clue what it will write next. It simply guesses what the next word will be based on what the last word was.
Another failure of these bots, they're Pre-Trained. It's the "p" in the name. So anything they generate will be based on the training data, with no changes to the algorithm based on interacting with users. You can "convince" the bot of anything and the second you close that browser window, the bot basically resets to factory defaults.