If you give up then the VA wins, don't give up you can still overcome the VA denying you for OSA. I was first denied because the VA stated I was overweight and because I was getting older. I had to spend the money to get an IMO to overcome the denial at the BVA level. I did not want to spend money just like everyone else to prove that my disability was SC. You need to look at it as an investment, how much more you will get if you are approved for OSA at the 50% level.
There is a lot of excellent advice on this website and you need to decide whether that advice is applicable to you. You are the only one that can make that decision no one else can for you.
Good luck!