Yup! He just needed somewhere to hide in, as most bettas do. A couple of mine LOVE their caves and cups and will be in them on and off throughout the day and "sleep" (their rest stage) in them at night.
Bettas prefer a fuller tank with plants and decorations over sparse and empty tanks- males especially love a cave of sorts to hide in. With so little in a tank, there is no mental stimulation for them and that, in turn, can cause some problems.
Beautiful guy you have there.. nice big tank, but I highly recommend putting in some medium to tall plants in there (silk or live) so that he has something to do and explore. One of the possible reasons large finned ones such as one you have start to tail bite, is from lack of much in their tank. So just thought I'd throw out a suggestion, to make him happier and feel more secure :)