Why is Jainism less popular than Buddhism?

Jainism predates Buddhism. The religion has around 5 million followers, the majority of whom are in India. Buddhism has more than 500 million adherents. This huge disparity in the number of followers can be explained on the basis of the following reasons.
Jainism expects its followers to follow a strict monastic lifestyle to the extent that monks of the Digamabara sect do not wear any clothes. Rituals such as Sallekhana, where an individual chooses to die after giving up food and water, make this a very austere religion to follow.
Jain monks cannot travel by sea. This made proselytizing difficult for the early converts. Buddhism spread via land and sea routes. Japan and Sri Lanka are island nations with sizable Buddhist populations.
Jains extol nonviolence as the highest virtue. Followers who suffered attacks on their properties and temples could not strike back without contravening this basic tenet of Jainism. Buddhism expects its followers to avoid violence but not with the same rigidity as Jainism.
Jains restrict themselves to a strict vegetarian diet, eschewing even roots and tubers. Though Buddhism encourages vegetarianism, it does not places a strict restriction on its followers.
Jainism did not receive much royal patronage. Buddhism, on the other hand, was patronized by kings of many dynasties such as Sunga, Gupta, Pala, and Khadga.