Firstly unless you use your power tools full-time you should consider renting them out. During the weekdays we do our work and mostly rest in the evenings. Power tool projects are mostly done during the weekends when we have all day to work on our power tool projects.
If you are serious about renting out your power tools there are online websites you can check. Just Google “rent out your power tools” to check out articles on how to rent or rent out your power tools and for that matter almost any items in your house.
Now that we have discussed the most obvious way to earn money from your power tools let me discuss how some people who “seldom” use power tools “think” about them. When I mean “seldom” I mean months or even a year passes by without me touching them. When I mean “think” it means “power tools are dangerous and unwieldy”.
The angle grinder for example is a handy tool I use for cutting and sanding objects but whenever I use it the thought of the blade getting unstuck or breaking into pieces and cutting and hurting me is always in my mind while using it. It does not help that I also read reports that state that the blade getting unstuck and breaking into pieces is not an uncommon thing which further terrifies me and other people I know.
Because the angle grinder vibrates a lot and is also heavy I always fear I will lose my grip on it and it will become loose uncontrollably and cut and damage anything it touches or worse make contact with my body and cut and injure me. It also does not help that I have to grasp it with one hand only.
These 2 areas of concern from the angle grinder has similarities with other small power tools that are not mounted for example in work benches and have no shielding for the user. I have yet to see such issues addressed by the power tools industry.
Enterprising people can earn money by addressing these issues and make accompanying products for power tools that make them safe and easy to use. Even wooden versions of such products would already be effective and can be constructed easily even in a garage at home by a beginner or smalltime manufacturer.