Your invention is only valuable if it is properly protected.
Unless you decide to keep your invention a secret, the only thing that can keep people from making, using and selling it without your permission is a patent.
SURPRISE: The United States Patent Office does not want you to get a patent.
A patent will issue on your invention, only if the best efforts of USPTO patent examiners are thwarted. Patent examiners are highly-trained, technically-gifted government employees who get paid to make sure that nobody gets a patent without a fight. Think about it! A patent gives you the right to exclude others from making, selling, or using your invention. The US government does not want you to have this monopoly. They grant patents only when they absolutely must in order to entice inventors, like you, to disclose their inventions to the public.
Do not get conned by fraudulent invention promotion firms or over-simplified do-it-yourself websites & books. There's a reason that Patent Attorney's have to pass an additional bar exam. There's a reason that Patent Attorney's are required to have a technical degree. There's a reason that the pass rate on the USPTO bar exam is typically 50% or less. Patent law is complicated. Even The United States Supreme Court (in Topliff v. Topliff) has said that a patent application is one of the most difficult legal documents to draft. You need a professional.