All the opposite. the effort you put into keeping a social circle of quality friends and acquaintances in your 30s and beyond can be extremely rich in terms of pleasure, social activities, and even work or business connections, and there's nothing whatsoever about being older that makes you a "child" if you actively cultivate irreplaceable time with good friends. Nothing about cultivating and keeping friendships in your later years stops you from pursuing rich personal interests either. It sometimes even achieves the opposite and nurtures rich experiences or interesting projects.
We are fundamentally, innately social animals, and that extends to more than just family and work circles. To each their own, but your view is snidely dismissive of an enormous source of happiness in so many people's lives.