Referring to the OP, the creation of the S&W 500 follows (late) on the heels of the .44 Magnum, following on the heels of the .357 Magnum, all originally created as HUNTING handguns for large North American game such as Caribou, Elk, Moose, mountain Lion, Bighorn Sheep and smaller bears. The .454 Casull, .475 Linebaugh, and also Ruger .460 were competitors offering’s in the sport of **HUNTING ** handguns. My father has taken numerous mule deer, white tail deer and boar using a .44 Magnum Super Blackhawk, which has an effective range of 100 yards. The newer calibers have now taken that effective range to 200 yards. In addition to the HUNTING uses of these calibers, many are offered in “Pilot” or “Tracker” barrel lengths (shorter) for easy carry and use against large predators such as Kodiak, Grizzly, Brown or Polar bears.
Just about the same thing a .45 can do to a watermelon, but easier on your wallet. 
Since RPGs are illegal, and since no one credible is advocating universal RPG ownership in the USA, that’s a bit of a non-starter.
Different country, different culture. Lets compare apples to apples, hmm?
Cite? And gun stores are a lot easier to steal from than the Marines, too.
Again, cite? If it’s Kellerman, he has been so thoroughly debunked, at-large and on this board, yet this butt-nugget of “fact” just won’t die, 'cause uninformed (or disingenuous) people like you keep clinging to it.
And once again, I’ll ask for a cite? Even criminals know the difference between armed robbery and murder, and the difference in likely sentences, and, more immediately, the amount of heat the latter will bring down.
Not every criminal is Hannibal Lecter, willing to eat your face and wear your skin for the loose change in your pocket. Even the dimmest criminal has some rudimentary notion of risk-vs.-reward, and their own sense of how far they are willing to go to get what they want.
Can you really? What if he can run faster than you? What if you can’t run 'cause of bad knees? With a firearm as an equalizer, the potential victim at least has a chance.
As a gun-owner for over 32 years, I’ve never accidentally shot anyone in my household over a midnight run to the toilet. Or fridge. Or for coming home late. Idiots keep trotting out this bullshit without the least bit of credible evidence that it’s any kind of danger at all (unless they happen to believe in Kellerman’s fallacious “43 times” fabrication")
Numer 2 is along the lines of competitive target shooting: Skeet and Trap, Cowboy Action Shooting, and Defensive Shooting (IPSC and IDPA).
Number 4 is a more of a discriminating collector, looking for certain pieces of some intrinsic or (more often) historic value. Whereas number 5 is my uncle Rich; he buys anything and everything he can afford to lay his hands on, often for no other reason than it struck a momentary fancy. He often resells (or trades) to various members of his gun club or VFW post.
Generally: the large caliber handgun has been and is being used as an effective hunting tool in North America for the better part of a century, now. Is it what everyone buys one for? Dunno. I don’t know everyone that’s bought one. Theories abound, from debunked pseudo-Freudian/proto-Feminist psychobabble, to terrorists shooting down airplanes, to people who like to own novel machinery.
And anyone who thinks the .500 S&W is an effective elephant gun had better not pack one on a safari, 'cause after the first shot, your dumb ass is gonna be primordial primate goo stuck between one pissed off elephant’s toes.
More likely, though, is that either your guide will boot you from the safari (for being an idiot), or your fellow hunters will shoot you themselves, 'less you gross stupidity get them killed.
As a backup weapon on safari, I’d imagine it’d do just fine.