I commute 5000 miles per year. In that time, if I ride only one bike, I’ll need to replace one tire — rotate the front to the back and put a new one on the front. I use nice tires so that one tire will cost me about 70 bucks. I patch my tubes. With a clean chain, I won’t need another one for 2+ years. If I need a new cassette, that is about two tanks of gas for two years of commuting.