A friend of mine went to an African safari guided tour, lead by a professional, on a truck. It was extremely clear that everyone had to stay on the truck because wild lions don't give a fuck about the whole "murder is illegal" thing. From what they told me, halfway through someone on the tour noticed a rhino, and without telling anyone jumped off and started running toward it with a file to try to get some rhino horn powder (they had missed the memo that rhinos are not exactly gentle creatures) and almost got themselves killed as the guide screamed for them to get the hell back. Supposedly when they finally listened, they came back explaining they just wanted to file down a little bit of the horns without hurting the rhino.
Some people are seriously self centered.