Education is key to success, however to really have the biggest springboard in life you need to mix it in with a few other ingredients. You ideally need a stable home when growing up with decent routines in place, even things like getting food on a regular basis is important. Being able to attend classes properly is key, because missing a few can really leave large gaps in your knowledge. Having a good higher education system or even things like apprenticeship courses which teach hands on training is important, because people learn better in different ways. You might also need funds to pay for things like additional tutoring, supplies for school and even things like transport all get rather expensive.
Education is one option for people to be successful but that doesn't mean education is the key to success because I feel that education, especially for now, can no longer be used as a benchmark for success.
Now the era has become more sophisticated and with the education system as it is now, actually this stigma seems to be slowly being pushed aside with some people even being able to succeed without a first level of education.