Working While Old

I'm 55, 56 in a couple of months and reentering the workforce.
I am lucky enough to have retired in my 40's and have a huge investment income stream so working is optional.
Why work? I've moved to my mountain dream house in a small town. Working outside of the home will help me become a part of this community and make friends.
Many older folks work to supplement SSI or investments while many are like me and want the opportunity to socialize.
My Dad worked most of his life too. He was terrified he would die if he retired fully as both his Dad and brother passed within months of retirement.
It's also fun to mentor. I have over 20 years in IT at a large corporation. I bring skills to this small business that simply don't exist here and I'm hoping we learn from each other.
People are also living much longer and while my investments will provide until I'm 109 you never know what the future may hold.
Many people invested with a plan that sees them financially set until around 75. What if you live into your 90's? Eat catfood? Nope, I'm too spoiled by my garden for that!
Some older folks are finally at a place in their life where they can have the job they always wanted but they didn't pursue when they were younger for different reasons.
To sum it up, working into your golden years is YOUR CHOICE. Whether by financial need, desire for socialization, or just to stay sharp, we old farts are here working and thriving.