You are making far too many generalizations about people in their 30s.
Not true. I was making generalizations about single people in their thirties. Perhaps it's different for you, but I work for a large corporation and the vast majority of my married coworkers own their own homes and live relatively responsible lives. My single coworkers mostly rent apartments and party on weekends. When we talk about how the 401k or the company stock is doing it's always among the married guys, since we're almost all participating in these plans. When it comes to cars however most of the old beaters, economy cars and work trucks belong to the family guys while the single guys ussually have newer, faster and more expensive cars and trucks.