Of course people have survived this cancer for more than 20 years!
That's just how they list out the survival rates for all cancers. They don't mean that people die after that long. With Papillary Thyroid Cancer, 80-90% survive AT LEAST to the 10 year mark. That's amazingly high! Some sources even put it higher than that (saying above 90%). After 10 years, they sort of stop counting. You can't track people forever.
My ENT told me that he once read a study where they found that people with early-stage thyroid cancer actually lived longer than the general population and they thought it was because they got a higher level of medical care through their lives. After all, we have to go to the doctor a least once or twice a year, get blood tests, all that. Some people don't ever go to the doctor, even when something's wrong. We know better.
What you have is treatable and very very very probably curable. You could have gotten something a whole lot worse. I know this may sound weird, but this is a time to be grateful. They caught it early, they know what it is, they can do something about it. The treatment is much easier compared to other cancers. If you do have RAI, it's a weekend out of your life, not months of chemo and radiation. NO hair loss or anything. You're also not in any pain. So many things to be grateful for.
Above all: you have a family that loves you and will be there for you. It's the summer time. Go take your kids to a water park or go camping or plant a garden. Live life.
I hope that helps, at least a little.
--Myrah