The game currently has an average user base of just over 20k players and is dropping by the thousands every day. Going to a live service model wouldn't necessarily make them more money or be as sustainable as simply moving on to a new game.
They also might not be that great at managing money. They went from barely known to having a flash-in-the-pan hit out of nowhere. Plenty of other devs have collapsed under the weight of their own, similar successes because they couldn't figure out what to do with it.