I see you have zero knowledge of the history of tattooing and piercing. And probably even less interest in learning it or why people do it.
If you mean the historical roots of these things, yeah, who gives a rat's @$$?! I do know that in modern times, up until quite recently, it was indeed the seedy underclass who did these things. I'm old enough to have seen this. As to why people do it now: herd mentality, of course.