How many mentally ill and sick People fought during the Revolutionary War? It is said that about 17,000 died of disease and sickness.?

In almost all wars more people die of disease than die of battle wounds.

"How many mentally ill and sick People fought during the Revolutionary War?"

It's impossible to tell because 1) complete and accurate records of such things weren't generally kept, and 2) many of the mental illnesses/conditions that medical science has identified today were undiagnosed/unknown back then. For example, someone with Asperger's syndrome is diagnosed relatively easily in 2019. Someone with Asperger's syndrome in 1776 would probably just be chalked up as merely "being a bit eccentric". Same for someone with ADHD. Someone with clinical depression might have simply been thought of as "someone with a melancholy demeanor". More severe mental disorders were simply referred to as "madness"; the reasons were poorly understood back then.

"It is said that about 17,000 died of disease and sickness?"

Yup.

Many more Americans died from disease or malnutrition while being held as prisoners of war aboard unsanitary British prison ships in New York Harbor than were killed in combat during the war.

They thought that malaria came from breathing bad vapors around rivers and you could die from tooth decay. So it is no wonder.