Why can't you win a lawsuit if you have a patent?

First of all, the patent may be invalid, and the invalid patent is regarded as having no patent right from beginning to end, so there is no infringement problem. In addition, a patent has a scope of protection, which is determined by the patent claim and has little to do with the specification and drawings. , so it is likely that the scope of the patent claim is so small that the inventor thinks it is infringing, but it is not. In addition, there is still some uncertainty in litigation, and different judges and lawyers may get different results. Therefore, it does not mean that owning a patent will definitely win the lawsuit.