Recurrent UTI's usually need to be investigated. They can be caused by any type of thing that blocks the flow of urine in the urinary tract which can be in your urethra, bladder or kidney. Kidney stones, for example. Kidney disease. Anatomy that is unusually shaped. You could have a genetic predisposition. Men should also have their prostate checked if they have chronic UTI's as that is a common cause of this recurrence.
Not sure why anyone would opt to not treat a UTI since they are uncomfortable. They 'can' clear by themselves from time to time but if you have chronic uti's, the underlying reasons should be investigated. If you have an underlying kidney issue, this could lead to long term issues, for example.