Here we go again i thought we're might to read replies before commenting. Like other users above have stated age isn't a factor when it comes to investing. You have to change this your school of thought because, it's wrong.
I believe it's said, "the youngs are the leaders of tomorrow" now when investing do you do it for today or tomorrow?  If it's tomorrow then why invest in a start up that might be dead before tomorrow when the young will be the leaders? considering your statement of investing because of age.
 The safest starts up are does that'll stand the test of time and they should be considered first when it comes to investing irrespective of the ages of the founders putting into consideration that smarter minds can always take over the vision of the startup. Invest in the vision not the age.