Compared to the cost of drafting, litigation, etc., the actual filing fee for a patent is a ridiculously small sum of money. If the patent office has the obligation to review a patent with the same attention to detail as the authors themselves, why doesn't it cost tens or hundreds of thousands of dollars to file a patent?
It is not the patent filing fee that matters. It is the litigation costs when some entity willfully impinges upon your patent. Big companies can afford litigation and often cross-license patents.
What costs is getting an attorney to write it in such a way as to see it awarded.<p>While <i>in theory</i> you can write your own (and file for the small fee), in practice your self-authored application won't be awarded a patent and your invention will become free public knowledge.<p>Nearly all parents are awarded to big companies with massive teams of lawyers. The "little guy" patent is mostly a myth.