If last week’s market tumble has you worried about your 401(k) or Roth IRA investments, you’re in good company—even the ultrawealthy are feeling the pain. Six out of the 10 top richest people in the world have experienced wealth declines between $30 billion and $60 billion this calendar year, totaling over $255 billion. Jeff Bezos’s net worth is down $30.7 billion since January, whereas Mark Zuckerberg has faced a decline of $46.3 billion in wealth, according to the Bloomberg Billionaires Index. The sha ...