What is the number one financial regret of Americans? According to personal finance website Nerd Wallet, it turns out that roughly 71% of Americans express regret about their ability to manage their money. First on the list was not planning early enough (48%), followed by too much spending on non-essentials (39%), credit-card debt (33%), and not having a budget (32%). While baby boomers led in the way in the "not planning early enough" category, Generation X and millennials were tied in regretting spending on non-essentials.