Ambedkar didn't convert to Buddhism. He virtually created a new religion and force-fitted Buddha into it, as he had earlier theorized that Untouchables were Buddhists men who were vanquished. The Navayana Buddhism that Ambedkar created is primarily based on negation of Hinduism rather than seeking any truth or peace. It builds a negative identity rather than something original of its own. Possibly no other religion, not even Islam, is so strongly based on negation even though the Islamic shahada literally begins with "there is no God but Allah"; it's a generic negation, rather than specific one that Ambedkar introduced through his 22 vows. Pagan religions were wiped out from Arabia but Islam survived as it didn't merely create a negative identity. Possibly that's why Islamists like Sharjeel Imam love Ambedkarites. He knows, rather hopes, that once the original target is finished, a negative identity can't survive for long. It's a fertile ground for second round of conversion. It's another matter that Christian missionaries end up winning that round more successfully.