ELMBROOK, WI—Although he earns a salary in the low six figures, 38-year-old investment banker David Monreal said he will always stay true to his middle-class upbringing. "When I was a kid, both of my parents held down jobs just to help pay for our split-level ranch home and two Chryslers," Monreal said. "Mom used to have a rule: no TV during supper. No matter how big my portfolio gets, I'll never forget that rule." Monreal said he hopes one day to take his kids to the office where their Grandpa Joe toiled selling insurance for up to 40 hours a week.