In "Blood Match", Dino's friends, on an attempt ro recover a photograph ofDino's brother from Stavros Garkos, they instead take a photograph of somebody they have no idea who he is. Given how old that photo can be, I believe it might be from Stavros Garkos during his young days and that he liked to play soccer as a child.
Also, in that episode where Garkos tried to gain access to a mind-controlling plant, Plato and his brother use in on Garkos and, to make sure he wouldn't exploit the Amazonian Jungle, used it on him to make him "confess" wrongdoings he did to become wealthy. While we can't be sure of the truthfulness of those confessions, it's easy to believe he might have started his fortune through scams.
Does anyone want to discuss this or come up with other theories?