Do they just forget that one of their miners is mining it? Take Zetacoin for example. Prime example. It has a hash rate of about 26 Th/s (SHA-256 algorithm btw). No developers listed on their website, price chart shows it has 7+ P&D attempts, last commit on Github was months ago (April I believe). So why do miners still put hash power into these coins when there's no future for them and profitability keeps dropping?