Are there workplaces which truly value the skill that older people can bring to their businesses? I haven't found them. But an experienced worker as a freelancer...now that's another situation.
The entrepreneur's image is necessarily based on their work ethic, personality and talent. A young adult stepping out into entrepreneurship may be perceived as not yet having the skill and authority necessary to not only run a business, but also to provide superior service to clients.
However, a middle-aged individual (and older) has reserves of business and life experience just waiting to be tapped. The sage, the expert, the wisdom-keeper. Assuming we have good work records, we have earned the respect of our associates and network. People tend to think, "Well, if he (she) has come this far, he (she) must have a lot to offer."
I am happier in work than I have ever been, and happier in my life as well. These, of course, are closely intertwined. Now, I am grateful for that shove off the cliff, although at the time I was terrified. I have, like that wonderful bottle of Cabernet, aged to perfection...and I know I will share my "sage-ness" with clients for years to come!