What does successful mean? Raised a million in funding? Sold company for a million?
What is a blog? Is a magazine/newspaper turned digital considered a blog? Does a press release written by someone else count?
What is an entrepreneur considered? Someone who just started a company (less than 1 year)? Someone who's started 40 companies over 30 years?
Probably the most well known entrepreneur blog by what is considered a highly successful entrepreneur, is Richard Branson - http://www.virgin.com/richard-branson - but as far as I can tell he doesn't actually write any of it himself.