Since the Buddha says that all beings are equal, why are some people born with disabilities?

The Buddha said that people have three causes, namely the so-called cause and effect. People come from reincarnation, and there were many bad karma in previous lives, so they were born with disabilities and there was a gap between the rich and the poor. Therefore, people are born equal, and health and wealth are cultivated. Buddha, try to believe with your heart that there will be the answer you want.