So the question is "why you if I can hire a 23 year old with possibly more energy, less baggage (most likely they can work longer hours and not have family/kids to worry about etc). That's possibly ageism but when there is a choice b/w an entry level Software Dev who is 23 vs who is 42, who do you think will get priority ?
Now, if you can differentiate yourself where your age becomes a plus and not minus, then we are talking. For example, one can assume you have a lot of real world experience, you have worked in tough conditions with real customers (whatever industry). Can you use that to your advantage and make a better case ? Then you can do it.