I think suicide falls under the category of criminal activity because it results in the death of a human; in this case the self.
It's in the word itself. The suffix "cide" is the act of killing. Homicide: killing a person; suicide: killing onseself; genocide: killing of antire group of people; omnicide: the destruction of everything.
The laws and penalties on suicide vary from place to place. Intentional, accidental, whether or not it resulted from a mental condition are all factors. I know in some cases the offendors' estate becomes the property of the governing body rather their heir(s). A real shit deal.
In the Middle-East, at least among Arabic nations, it is considered shameful. The offendor is considered a disgraced coward or a jackass. Usually the family and friends that feel are the ones especially offended by the suicide. Socially, no one talks about it, it's considered a distasteful subject.
I believe any person has the freedom of will to choose anything they want to do; it's just a question of whether or not they're willing to pay the price or suffer the consequences. Basically risk and cost assessment. Nothing is free, fair trade.