Why is it that some people believe that metal illnesses are not a thing?

They base it on experiences with people they have had in the past

People who don't believe in mental illnesses think the person with the mental illness is just lying about it. people may not believe in them because it's not like a physical illness where you see the symptoms or you clearly see that the person is sick. it's just the matter of not seeing physical proof of the mental illness.

Do you have a picture for this question?

Dis correct. the rest of the answers are definitely wrong.without the basic needs like food, shelter and love , one will remain trapped in trying to fulfil these needs first which means putting food on the table and struggling to pay bills. it is impossible to achieve self actualization when without the basic needs which is the base.