It is whatever you buy a battery and charger for first. Then you are unwilling to forfeit that battery to just buy another tool. So you get another tool of the same brand, even if you aren’t happy with the previous. Then at that point, you’ve gone to far. You’ve got several hundred dollars in batteries you would have to give up just to switch. It is the most blatant example of the sunken cost fallacy.

Ryobi, specifically has entry level tools (a basic drill) that come with a charger and battery for cheaper than you can even buy a battery by itself. When you’re young and broke and all you need to do is hang some curtains or something you get it. But really, it is just a seed for your future “house” that you belong to.