Jim, Alice and Rob Walton are big winners from Walmart's stock surge this year.REUTERS/Rick WilkingWalmart stock has soared 58% this year to record highs, making its founding family richer than ever.Retail legend Sam Walton's three surviving children are each worth more than $100 billion.Walmart and the Waltons have benefited from a signature strategy and cost pressures on consumers.Walmart stock has soared to record highs, lifting the retailer's founding family to new levels of wealth.