Why do manufactures do this?

Why do manufactures do this? You buy a widget for $2—$5 and it comes with batteries, lets say those little silver ones that look like tiny shinny hockey pucks. All is good they last several years or close to it. Then you have to buy new batteries, but the new batteries cost as much as the widget did new, and if you have to use more than one battery the cost of to keep using it can exceed the original cost to buy. Then you have a dilemma, in the case you can still find and buy the widget it maybe cheaper to buy a new on with fresh batteries than keep the old on which still works perfectly but doesn’t seem to warrant spending more money than it is worth to keep using it. If you go the new route, the old one will get tossed out eventually even though it still works. Why do manufactures do that? Why make a widget in which the replacement batteries will cost more than the original item?