That depends. Sure, if you have a burning need to do a certain task and are looking for a product to do the task, then you are absolutely spot on.

On the other hand, here is a cheap toy. And - yey! - it can actually do stuff! Why don't I buy one and play with it? There. A niche filled

I love it. 95% efficiency. But I would say that's way too wasteful. A good heatball should give at least 98%.

BTW, this sentence took me three reads until I got it. What a difference a missing comma makes: "The input energy that a heatball consumes is the effort, its heat is the benefit while light portion is the loss." (Missing comma after benefit.)