People have been having ether frolics and later, laughing-gas parties ever since. In the proper hands, ether remains one of the safest inhalation agents known. Some of Dr. Larch's colleagues would have preferred nitrous oxide or chloroform, but Larch developed his preference for ether through self-administration. You would have to be crazy to self-administer chloroform. It requires careful monitoring and cumbersome apparatus, and the patient runs the risk of bizarre fantasies or giggling fits.
Induction is very fast.
Coleridge was a laughing-gas man, although the poet was certainly familiar with ether, too. It was unfortunate for Coleridge that he preferred opium. Ether is a kinder drug addiction to bear. But no drug addiction is without risk and no self-administered anesthesia is safe. After all, in both the novel and the film, Dr. Larch accidentally kills himself with ether.