Why do you think Alexander named so many cities after himself

One word. Vanity. Hubris.

He was obsessed with leaving his legacy and being remembered acrosshis empire.

In times before people invented the idea of an afterlife, theycould live on in people’s memories – if people remembered them.Everyone remembered Achilles, even though he was a callousmurderer, because the bards sang of him. So self-important peopletried to be remembered. Alexander’s naming of over 30 citiesAlexandria after himself reflected this. He even named a city afterhis trusty horse Bucephalus to keep his name alive, and similarlyfavoured some of his generals.