That's not quite true - HIV of course mutates but in-patient mutations are generally considered to have a negligible effect on outcomes/have a negligible effect

That's not quite true - HIV of course mutates but in-patient mutations are generally considered to have a negligible effect on outcomes/have a negligible effect as a driver of morbidity . What is the big driver of HIV is in the name, it's a Immunodeficiency virus - it kills CD4+ T cells and other cells of the immune system. At a certain point you don't have enough CD4+ T cells left and you lose your adaptive/cell-mediated immune system and then you're in big trouble. Essentially it's a war of attrition and unless you're part of some tiny proportion of people who have either a form of immunity against it or an immune system that for whatever reason is able to continue waging war on it then you will succumb