They’re expensive because they could be the basis of preventing other people from practicing your valuable product, or a close alternatives. They are only useful, if someone is actually making your product, and you do it in order to protect your product. ergo, you don’t bother to use it, at least to good effect, where you are in the business of making the product that you might want to have protected with a patent. That entity, ought to have a reason that represents such a potential loss of business, that the amount worth seeking is well in excess of the cost of getting a patent. So, while getting a patent seems extremely expensive when you are just a small entity or individual trying to get started, it has to be done at that point, so that the ultimate entity seeking to use it has a chance. It is a bet. it’s only worth it, if it’s would be worth protecting when someone else starts to imitate it. So you have to ask yourself, is my product something that will be worth enough, when it’s able to be used by a sufficiently large practicing entity? if the invention is good, then maybe it’s a safe bet, and so maybe the cost isn’t too expensive to be worth its price.