As such if you go to see thn eating potato everyday may nt damage you in anyway, but yea eating only potato may b wrong as you should always incorporate variety in your diet to meet all your essential vitamins and minerals
requirement. potato contains only starch and some vit C nt much of nutrients therefore i wont recommend you to eat potatoes only daily. you can have potato along with mixed vegetables and not alone.
And yea it is mainly starch soo you may put on wt with that. anyways repeating same food daily is nt healthy either. and if you r a daibetic then its not at all recommended to have potatoes
i hope this solves your query