No! The correct answer to this question is that you cannot go to Tomorrowland if you are under the age of 18. The minimum age limit to enter the festival is 18. You must be aged 18 years old or over. If you turn 18 in the year of the festival, you can gain entry to the festival. This is the only exception to the policy.
The age restriction is vigorously enforced, and you will be required to provide proof of age upon arrival to the festival. There are no exceptions to this policy, even if an adult accompanies you. Failures to prove you are above 18, you will not be granted access to Tomorrowland. I hope you find this information useful.