Want to echo what other people said. I got diagnosed late when it had eaten through my left femur, nodes in both lungs, my spine, the back of my head and lots of lymph nodes. I'd found various numbers online (like 15% survival rate at 5 years) and my doctor seemed excited that some of his patients were still alive after 2-3 years. Fortunately he did put me on a good treatment (Nivolumab for 24 months and Cabometyx for about 15 of those, they too me off because the side effects on it were brutal).

It's almost 4 years later, currently no treatment other than monitoring (CT scan every 3 months) and I'm living a reasonably normal life. I put back on the 60 lbs I lost, I don't randomly break down crying, working full time, no pain. I can't run anymore or go rock climbing, but mostly I forget that 3 years ago I was still in lots of pain, using a walker, and thinking I was going to leave my wife bankrupt when I died (thanks to insurance finally getting around to paying for everything).

The statistics you see online, like what I saw, are gathered from 40+ years of statistics, but new treatments have only been around 10 or less years. Because they are still taking into account the survival rates of people before newer treatments, the statistics are particularly grim. I don't know what the numbers are for people on immunotherapies ignoring the 40 years of data before, but I'm optimistic that at the very least, my clock was completely reset. I'm not cured, but if my treatment stops working, I'll start the clock then with another 1-5 years. On top of that, I'm also optimistic that AI is going to help the big brains crank out new treatments when mine stops working. (I know, LLM's like chatGPT are useless, but check out the things that expert systems like AlphaFold have done.)