That's a great question. With their natural life span you'd think they'd have a little more energy for things wouldn't you? But there is that problem of them going dormant for long periods of time, fifty years at a clip right? Maybe the very biology that makes them live almost supernaturally long lives has a high price in consumption too. A lion on the Serengeti plain must rest and conserve energy between hunts otherwise they waste valuable calories for nothing. Maybe that's the Wraith's problem with diversification as well. Human's live shorter but perhaps more productive lives.