Unless you have a great and proven business idea that's already taking off, staying in school and getting a degree seems to have a closer correlation to success than dropping out.
The problem with statistics in discussions like this is that they don't really mean anything. Sure, the statistic you mentioned shows that 64% of business owners have a Bachelor's degree, but it doesn't show that having a Bachelor's degree is useful in starting and running a successful business. This is a common flaw with statistics.
Example - Most successful tech entrepreneurs are male (let's say 9/10). That doesn't mean that women are only 1/10 as likely to succeed in that space if they tried, it just means that most successful tech entrepreneurs are male.
People with Bachelor's degrees are likely higher than averagely smart and ambigious people with successful and supporting parents. Who knows what would have happened if they skipped over the degree they felt they needed and instead jumped right into starting a business. Sure, it would be very tough in the beginning, but I'd bet that they would reach their goals faster than delaying the start 3+ years. Ambition is correlated with success, a degree is just correlated with ambition.
Dropping out of college is, quite obviously, not positively correlated to success. Most people who drop out do it either because it is too hard/too much work or too expensive. However, I think that people who drop out (or not start at all) not mainly because of those factors, but because of a strong drive to reach their goals faster are just as likely to succeed (if not more so).
It's transparently obvious from looking at data that getting a college degree is correlated with success, assuming success means having more income. The gulf is significant and growing.
But all that really tells is that there may be some correlation to the attributes of a person which allows them to make their way through increasingly challenging levels of education (smarts, drive, luck, etc.), also allows them success in business. It is more than likely those attributes were present before entering college. Perhaps even as far back as birth.
64% of US business owners have at least a Bachelor's degree (source: http://www.census.gov/econ/sbo/02/cbosof.html).
Unless you have a great and proven business idea that's already taking off, staying in school and getting a degree seems to have a closer correlation to success than dropping out.