This is the point - if you catch it early then you’re pretty much grand unless you’ve got an aggressive form of it. Spot of hormone therapy and regular monitoring is all that’s needed. My Uncle’s went a bit full blown last year so he had a course of reasonably uninvasive radiotherapy and it’s cleared up for now.
You’re more likely to die with prostate cancer than of it, if that makes sense. Most of the people who die of it either a) have an aggressive form which metastasises rapidly (in which case - unlucky) or b) have had it undetected for years and didn’t do anything about it until old age where your body is unable to fight it. But yeah in most cases (like my Grandad) he died of lung cancer but when they did the post-mortem they were like “ah he had prostate cancer as well”.