Fleas

So I have a cat. Well a kitten. Just the one pet no others. He had fleas when we got him and gave him a dawn bath as soon as he entered our home. He’s had four dawn baths and I’ve combed him with a flea comb and soapy water multiple times. He’s been here about a month. We are finding fleas in our home and their feces I assume it is (little black specs). Wash everything and vacuum. Why do we still keep having them? Do all animals indoors have some fleas no matter what? Like will we always have do deal with a few or can we make it completely flea free? I hate bugs! He’s about to be 12 weeks old.