According to a poll conducted by the National Association of the Self Employed (NASE), it's not looking so good. Thirty percent of respondents to NASE's poll said they have no savings for retirement; 25% have less than $15,000 stashed away for their golden years. Startupjournal.com's publisher, Tony Lee, said in a press release that owners like to keep cash on hand in case of emergency, and "prefer to invest earnings into the business rather than setting aside the money for retirement."
There's an argument to be made that investing in the business is investing in retirement, since it's feasible that selling the business could fund a retirement. However, ignoring tax-advantaged ways to save for retirement seems foolhardy. Depending on the sale of your business to fund a nest egg is kind of like saying "Social Security will take care of me." You just don't know what either will be worth when you're ready to exit.