You've already set up a game where "dying" leads to half of your treasure randomly disappearing for some reason. You've already turned the game into a MMO/Soft Core Diablo style thing, and you're surprised they're not taking it seriously?

Which isn't necessarily to say that they'd suddenly turn into good players if the game made some sort of actual sense. But it at least seems slightly more likely. The rest of the solution is probably "find better players".