By Ellen Chang Post-earnings rout hammers net worth of retailer family in largest drop since 1987. If the decline in Walmart shares continues, Sam Walton’s heirs may have to start shopping at the discount retailer themselves. Walton family members lost about $19 billion in one day after Walmart (WMT) – Get Walmart Inc. Report cut its profit outlook on Tuesday as consumers reined in their spending amid higher inflation levels. Walmart’s stock slumped by 11% after the weak earnings report. Shares of Walmart dipped by 6.23% at 2:20 ET as the broader market sold off. The Walton family heirs contro…