Tom,
I could have dictated your post from memory. I had the same feelings that you seem to be expressing.
I was 27, I assume you are older than me, so we'll say 45'ish. Doesn't matter.
My 2 cents worth...
Money..was important to me until cancer took all I had and then some. I lost everything to the tune of over 1 million dollars. I lost my practice, my home and my credit rating.
I will not live long enough regardless if I had cancer or not to ever recoup that loss. I really could care less. If I have my family around me, money doesn't matter. Some of you will be chewing you nails...saying Mike's a dentist he doesn't have to worry about money. I don't worry about what I don't have. I have no savings, massive credit card debt, huge loans that built my office. (I'm happy...yeah I read that and had to slap myself.)
If I had not had a wife and a son when I was diagnosed I would not have had the treatment.
You have three grandchildren. I envy them, I don't remeber my grandparents. My son has all four and he loves every minute he spends with them.
I'll leave you with this...Life is a fight, more or less, It's up to you to decide if it's a pillow fight with your grandchildren or bare knuckles with your brain. I used to get angry and beat myself up by overthinking and analyzing every aspect of what I was going through. It wasn't healthy for me, but be reassured Tom we all have had similar thoughts.
I wish you well and pray for you to find some comfort with any decisions you decide to make.

Cheers Tom, by posting you have said what I'm sure so many wanted to but did not. Yes, In my 5 months here we have debated this a couple of times. It doesn't hurt to share your thoughts and is certainly bound to help someone else.

Take care,

Mike