How much is enough?

When I was a young man in the USAF making $271 every two weeks, I knew I wanted more, I needed more to enjoy myself and more importantlhy, not have that edge of fear, the sense of disaster looming around every corner or mistake.

It's 25 years later, I've been at a sucessful technology company, I have several million (yes, million) dollars in the bank, and I still have the fear.
If I spend $100,000 per year, and ignore any income from investments or interest or anything, I have enough money to last me until I'm 80. 80. 80, and probably in my dotage. Spne less, and I last until I'm 100.
And still I fret.
What the hell.
If I had a billion dollars, would I still feel this way?
What's the pressure that drives this? What's the right amount? Am I reacting to reality, or to the weird pressures put on us societally?
Of course I also know that I could spend a million dollars in silly stuff in a year. Buy a fancy car for $500,000, spend $35,000 on a watch, upgrade my airplane to a jet, there are temptations lurking at every corenr.
The question is this, and the one I ask you to ask yourself: What makes you reallly happy?
I don't know yet. And I've got $3.5 million in cash.
What the hell.