疒 is one of the script's darkest radicals: a person lying on a bed, drawn sideways. Everything under it ails. 丙 lends sound. 病 is the picture of being horizontal when you'd rather not be.
病从口入 'illness enters by the mouth' is grandmother epidemiology — wash hands, cook thoroughly, drink hot water. 看病 'see illness' means visiting the doctor; 毛病 'little ailment' extends to cars, phones, and personality quirks: 这人有毛病 — something's off with this guy.
A person on the sick-bed 疒 — ILL.
网瘾 internet addiction was officially classified as a 病 in China before most countries had the debate — the vocabulary moved faster than the science.