Why does a patent not give us the right to use our invention?

The purpose of a patent is to incentivize an inventor to publicly disclose his/her invention by providing him/her a limited monopoly over making, using, selling, importing, or distributing a patented invention. However, the government won't pursue infringers for you. The patent only gives YOU, the patent owner, the right to pursue infringers for infringing on your rights -- rights that the government have granted you. This involves time and money but can usually lead to settlement. Of course, factors to consider are: value of the patent, size of the market, size of your company, size of the infringer's company, etc. A large company will sometimes not care if they've trodden on the rights of a small inventor since they know that the inventor 1) probably can't afford a case against them and 2) even if the inventor CAN afford it, he/she won't have the same resources that the big company has (money, suite of lawyers, researchers, access to expert testimony, etc.).

To answer your question, a patent DOES give you the right to use your invention. It also gives you the right to pursue others for using your patented technology.

Please let me know if this answers your questions.