Patent application filing fees and the time you spend preparing the applications, primarily. Also the loss of privacy (name, etc. in application) in applying fo

Patent application filing fees and the time you spend preparing the applications, primarily. Also the loss of privacy (name, etc. in application) in applying for the patent. Edit: Also the risk that your application is rejected so that you don't get a blocking patent, which would mean anyone else can use the invention or even patent an improvement. An improver might even cite your rejected application in their applications for more draconian inventions, which could be demoralizing.