Any individual who is above the age of 18 years should buy an individual health insurance policy. Even though this is an age where it is quite unlikely for the individual to face health problems, you can never be sure. If in case there is a health complication, it is always good to be backed up by an individual health insurance plan.
Also, since the individual is at a young age, it is quite likely that they are healthy and would not face any health complications in the near future. This is how they can get insurance policies at very affordable premiums. They can also also get a lot of coverage options by their insurer, which might not be the case when they start aging.