With the people I see covered in tattoos, it's pretty obvious that they aren't making a lot of money in their careers, and probably don't get much above minimum wage.
You imply that people who like to cover their body with tattoos are somehow less valuable in the workforce, but you have it backwards. It is not tattoo lovers being unable to perform, but society who rejects tattoo lovers. I have three tattoos so far and I make just shy of six figures. The only thing stopping me from being "covered in tattoos" is that many (most?) employers won't hire people with visible tattoos.
Before you reply with "oh then you're the exception to the norm," let me cut you off and say that you're wrong. I know plenty of others like me. You seem to think you can judge someone's income based on their tattoos (how exactly are you doing that again?) and then you reinforce your own beliefs by looking at others who fit your predetermined model. This is textbook confirmation bias.
Tattoos can be many things to many people (symbolic, art, memorial, decoration), but in general they are a form of self-expression. Like any form of self-expression, you're forgiven if you don't understand people's motivations. You should, however, show some respect rather than disparaging those who like different things than you, and you definitely shouldn't make the mistake of thinking you can categorize tattoo lovers as lower class and irresponsible. That mindset is poisonous and it's as ignorant as any other racial or cultural bias.