According to Mullin, on the other hand, it is improbable that the Manchus would have murdered any of these four for being 'unmanageable' since it would have been in their best interests to have strong Dalai Lamas ruling in Lhasa, he argues, agreeing with Richardson that it was rather "the ambition and greed for power of Tibetans" that might have caused the Lamas' early deaths. Further, if Tibetan nobles murdered any of them, it would more likely have been in order to protect or enhance their family interests rather than out of suspicion that the Dalai Lamas were seen as Chinese-appointed imposters as suggested by Norbu. They could also have died from illnesses, possibly contracted from diseases to which they had no immunity, carried to Lhasa by the multitudes of pilgrims visiting from nearby countries for blessings. Finally, from the Buddhist point of view, Mullin says, "Simply stated, these four Dalai Lamas died young because the world did not have enough good karma to deserve their presence".