“A man who is his own lawyer has a fool for a client.” The origin of that proverb is unclear, but may have been first uttered by an attorney. It may be true in complex cases, but in simple matters there's no reason a person of average intelligence can't prosecute his own case or defend himself if he can compile the evidence, present a persuasive argument, and follow the basic protocols of court procedure.
You walk past a BBQ joint, look in the window, and see a happy guy with some sauce on the front of his shirt devouring a rack of ribs, and it makes you feel good. There might be a tinge of envy, but you can tell he's enjoying those juicy ribs and you can't help smiling. That’s called vicarious pleasure.