What keeps the rich up at night? The fear of ruining their kids with wealth. A new survey by law firm Withers LLP and Scorpio Partnership asked 3,000 families around the world about their greatest fears regarding their wealth and family future. Among families worth $10 million or more, health was their biggest fear. But ranking second was, "My children will lack the drive and ambition to get ahead." The spoiled kids issue ranked ahead of "my investments," "I or members of my family will overspend" and "marital breakdown." The study didn't provide any solutions and suggested that no matter what rich parents try to do, large wealth can strain the family. The survey comes as singer Sting just said that he won't be leaving much of his $300 million fortune to his six kids. Bill Gates, Warren Buffett, Sandy Weill and other members of the wealth ranks said they prefer to give their fortunes to philanthropy rather than creating multi-generational dynasties. Sign up for top Business news direct to your inbox. IN-DEPTH Home Resales and Inventory Surge in May Stocks Slip From Record Highs; Iraq Oil Supply Concerns Weigh Every Time You Buy a New Car, You Become Less Dependent on Oil -Robert Frank, CNBC.com