The Reasons Why People Don't [Respect You] Become self Respect Now!!!

I don't know your full situation but i'll explain a few reasons why people don't respect others.

...Respect usually comes to those who have self respect.

People give off non-verbal signals that are an indication that they are relatively weak and unresistant to a person walking on them. They have a body language and posture that is closed, and some people see this and choose to take advantage.

Often when one person is being disrespected there are others who will join in. If you think of school where one person cops the majority of trouble from people, and then in no time everyone is joining to harass and abuse.

Sometimes people have such a low self esteem level that they get satisfaction from disrespecting others.

There's a solution to this and if a person is being disrespected they need to be assertive. Assertiveness helps a person to stand up for themselves to offer resistance to disrespectful people. If there's no resistance then the behaviour will usually continue.
      There are multiple strategies to offer resistance such as humour, using assertive language, and setting boundaries. It's when there's no form of resistance offered that the problem usually persists.