That helped take their collective wealth above $70 trillion for the first time and put them on track to have amassed $100 trillion by 2025, the Capgemini World Wealth Report 2018 found.
Only around 56 percent of millionaires say they are connected "very well" with their wealth managers, short of the 70 percent level the French business consulting group calls a passing grade.
Rich people's enthusiasm for digital currencies swelled last year, with 29 percent of millionaires expressing a high degree of interest in buying or holding cryptocurrencies and nearly 27 percent somewhat interested, the survey found.
Still, only around a third said they had got information about cryptocurrencies from their wealth managers.