Yes, school education is needed to be successful in today's world as school is a place of learning and socialization. Without the learning school can provide, one is ill-equipped for the challenges of the world, and the same can be said for the valuable socialization for which school provides opportunity.
We have all heard the story of the billionaire who dropped our of high school and started his own company. These stories are true, but they are few and far between. Having an education can open many doors that were once previously closed. Whether it is a collegiate or a trade school education, having higher learning will increase your chances of employment and advancement in today's global society.
Back up a minute. The question asked about school education, not any kind of education. Wikipedia used to have an article showing people who did bad in school, but were still successful. The list is now somewhere on School-survival.Net. However, what about the alternatives to school? Alternatives are better explained here http://www.school-survival.net/alternatives/ but essentially, school itself is not needed for success, only the education.
But you do need education. There is so many ways to receive a education outside of the classroom. You learn throughout life. There is a school called Sudbury valley school were there is no curriculum, the facility let students live life and do what they choose. Studies show that 80% of students went to college after this school. Some people will flourish with a school environment, but lots of students will need a free learning style to succeed.