48 Hours Investigates reports on Mary-Kate and Ashley Olsen, Frankie Muniz, Eric Trump and L'il Romeo -- Lifestyles of the young and rich. Rich Girls: The Olsen Twins: Even in Hollywood, where rich girls are a dime a dozen, these two 17-year-olds stand out. Mary-Kate and Ashley Olsen aren't just rich and ambitious, they're mini-moguls. And they're already worth, by some estimates, $40 million each and counting. Frankie Muniz: Hollywood Star: Actor Frankie Muniz has not only won fans -- he's made a fortune playing geeky teenage characters. On TV, he's the awkward, brainy middle child in the sit-com "Malcolm In The Middle." On the big screen, he's agent Cody Banks, a not-so-suave junior James Bond. In a few short years, the kid with the cute face and sparkling blue eyes has become one of Hollywood's most bankable teens. His salary for "Agent Cody Banks" was somewhere around $2 million – pretty good for Muniz, who just turned 18 this month. Correspondent Maureen Maher reports. Eric Trump: American Royalty: Eric is a prince to the manor born, part of that peculiar type of American royalty, who grows up behind the headlines with a gold-plated last name. Eric Trump, 19, is Ivana's baby boy and Donald Trump's youngest son. Correspondent Jane Clayson reports. Lil' Rome: Hip-Hop Star: Even in his wildest dreams, 14-year-old Percy Romeo Miller III never imagined a life like this. "Dreams can come true. Like Martin Luther King said, 'Have a dream,'" says Lil' Romeo, a pint-sized, platinum-selling, hip-hop superstar. In just two years, Lil' Romeo has sold an astonishing 20 million CDs. Now, he says he has $50 million in savings. This eighth grader stars in movies, cartoons and even runs a clothing company. When he's not shooting films, he's shooting hoops as a Junior Olympic basketball player. It must be a great life. "I mean Romeo's got cars, man," says his father, rapper Master P. "I'm, like, he can't even drive!" Lil' Romeo gave Correspondent