I know two couples who waited till their mid-30s to have children and after various miscarriages they both delivered boys with Down Syndrome, so was that worth partying in their 20s? No.
Not everyone who has kids in their mid-30s gets a kid with Down syndrome, and not everyone who has kids in their mid-30s does so because they were partying.
In whose opinion? It may shock you to learn that parents of children with down-syndrome frequently do not view it as the life-ruining event you make it out to be.