In general, films are made to be watched. I'm not sure I see the benefit in a film that isn't seen by anyone, unless it was just intended as a learning exercise.
You provide a couple of hypothetical benefits to shelving it, but to me they're no more compelling than the hypothetical benefits of releasing it yourself now. For instance building an audience who may buy your next film, who's very existence may be the key to selling your next film to a distributor, or who may support a crowdfunding effort for your next film's budget, etc. Plus, there's the real possibility that with some self-promotion & marketing effort you can sell copies - you may not make a lot, but I can almost guarantee it'll be more than what your film is making on the shelf. And any effort you expend towards that end will likely pay off towards the whole building a future audience part.
Of course there's also the concrete benefit - your film will be watched, which was presumably why you made it in the first place. If the only reason you made it was to sell it, well, maybe you're in the wrong business - there's a lot of other things that are easier to make a buck selling than an independent film.
You say 'never give up' and 'don't sell yourself short' - distributing it yourself doesn't have to be either of those.
