I have a good friend with Parkinson's disease.
My brother has also had it for years, since he was 25.
Objectively, my brother is in a bad way. But his attitude is terrific, and since his case is so unusual he gets a lot of medical interest. It is NOT true that there is nothing that can be done. This is a common disease, and there is a lot of research interest, and there are new treatments all the time, and I suspect that there will be increasingly effective ones. It may not be ideal, but by trying something new as your current treatment loses effectiveness sometimes works well. I remember my brother telling me once that "that treatment gave me two good years". He is wired up for deep brain stimulation, and that still gives him some benefit when they adjust it. He just refuses to give into it. I sent him something my friend sent me about a glove that supposedly interfered with dopamine processing and provided a real benefit. He was intrigued--he's always up for understanding.
There are also support groups. I can PM you some links if you like--one from Georgia, the other from Colorado, and you can do it virtually. It always helps to compare notes with new friends.
I have always hated Pollyanna sunshine stuff, but just sinking into a funk and giving in doesn't do anything either. I hope you can build an attitude like my brother's. And I don't think the medical outlook will always be as glum as it seems now.