Yes it is, but generally, laws are violations of personal freedoms. An idea sometimes summarized as "My right to swing my fist ends where your nose begins". It

Yes it is, but generally, laws are violations of personal freedoms. An idea sometimes summarized as "My right to swing my fist ends where your nose begins". It is less obvious with seatbelt laws, but the idea is the same. Generally, there are limits to the rights to kill yourself through recklessness. This is because it impacts much more people than you. If you die in a car accident because you didn't wear your seatbelt, first responders are going to try to save you, traffic will be blocked while the police investigates, your friends and family will be devastated, your employer will have to make up for the loss of an employee, other parties in the accident may be traumatized, etc... All that just for your personal freedom of not wearing a seatbelt. Lawmakers have decided that wearing a seatbelt does a lot of good to society at large (by not having to deal with reckless deaths) in exchange for a small violation in personal freedom. Sometimes it is hard to find a balance between personal freedom and the harm it may cause to others, but seatbelts are among the easy ones.