Doctors have a saying "if you're a man older than seventy, you will die with prostate cancer but you won't die from prostate cancer.". The only thing knowing you have it for sure will give you is stress.
Depends on the stage at diagnosis. If you have localized prostate cancer, I agree with you, you are probably good to go. A few years ago there was a recommmendation by a group of physicians (generally not urologic oncologists) to stop routine PSA testing in the US due a high rate false positives and 'over treatment'. This action has led to a dramatic increase in patient having metastatic prostate at initial diagnosis. Metastatic prostate cancer will give you much more than just stress, bone pain for instance.
