Advisory group deVere Group found 57 per cent regretted failing to devise a strategy for their personal finances sooner.
Other regrets included failing to regularly assess the performance of their investments (18 per cent), accumulating unnecessary debt (13 per cent) or failing to save enough for their children's education or to leave as inheritance.
The survey questioned almost 700 people with over £1m in investable assets.
Nigel Green, chief executive of deVere Group, said: "The poll shows that the number one 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.
{desktop}{/desktop}{mobile}{/mobile}
"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."
He said the fact many regret debts suggested respondents were trying to 'keep up with the Joneses' which negatively affected their wealth.
"A lack of financial discipline, which often manifests itself into a 'keeping up with the Joneses'-type mentality, is an enemy of wealth creation and those surveyed appear to now believe that this might have delayed them achieving their longer-term, more fundamental financial objectives."

• Want to receive a free weekly summary of the best news stories from our website? Just go to home page and submit your name and email address. If you are already logged in you will need to log out to see the e-newsletter sign up. You can then log in again.