> Because it usually only kicks in after childbearing years
Orphans are not a very good evolutionary tactics. But you definitely have a point otherwise. Had it earlier onset age, it would have no way to propagate.
Historically 30-50 would be often be grandparents or great grandparents which has much less evolutionary pressure. Though they would likely still have underage kids.
A 50 year old can have great grand kids, and a 3 year old at the same time. Though with a large extended family someone can also probably take over in the case something happens.
Orphans are not a very good evolutionary tactics. But you definitely have a point otherwise. Had it earlier onset age, it would have no way to propagate.