Millionaires’ biggest financial regret

The firm adds that 12 percent cited other regrets, including not saving enough to fund their children's or grandchildren's education or not having built a large enough estate to leave to their heirs.

"The poll shows that the No. 1 regret of high-net-worth individuals was not putting in place a robust plan for their personal finances which could be efficiently and regularly reviewed," Nigel Green, founder and chief executive of the deVere Group, said in a statement.

"With more than half of those surveyed citing this as their overriding regret, it's clear that wealthy individuals value highly the benefits and opportunities that long-term financial planning brings them and their families, and that they understand the importance of routinely reviewing those plans to ensure that they always remain 'on track' to reach their financial goals."

Green concluded that although the survey focuses on high-net-worth individuals, he suspects the same poll of middle-income earners would produce similar results. 

"As someone's wealth empowers them and their families to live the life they want to live," he said, "I imagine that any financial regrets would be fairly consistent."