I guess nowadays as far as new audience goes, it attracts mostly teenage boys.

For the rest of us, nostalgia plays a huge factor.


As for the movie's success in the 80s, it's such a mix of factors that as well said it's the zeitgeist. Those were fairly dark, depressing years. At one end of the spectrum you had movies reflecting this darkness and paranoia like Alien and Blade Runner (that gained an almost instantaneous cult status) - or in the realistic vein movies like Apocalypse Now, and at the other end of the spectrum there was George Lucas, who was offering something radically different and intentioannly breaking away with the "dark stuff" to bring back the "pure fun factor" in Hollywood, after a fairly long hiatus.

Indy when it came out was like the grown-up's SW. They're extremely similar movies in the end, with a really fast, action-packed pacing for its days, and both inspired by the old matinée serials - SW the Flash Gordon/Buck Rogers ones, Indy the adventure ones, SW with a retro-futuristic universe of Princesses and Knights, and Indy just plain retro. Indy cashed a lot on the SW factor - part of Lucas' genius was to have understood before most others the fact the world (and even more America itself) was ready again for old-style Hollywoodian hero movies revamped, for old plain entertainment, escapism. And in the lates 70s/early 80s, movies like Indy and SW really stood out.

Indy also had the Lucas name attached, the coolest of the Star Wars actors starring, and it had the Spielberg magic touch, and the operatic John Williams score. It was also a really slick movie when it came out. Nowhere as impressive as SW itself VFX-wise, but still way above average visually, while deriving its inspiration for the VFX from old cheesy serials. It's very well-paced and edited (like nearly all Spielberg's movies), and unlike Lucas in ANH, Spielberg really nailed the B-movie tone and acting perfectly (not that Lucas failed, but Ford's Indy is way, way better than Fisher's Leia or Hamill's Skywalker, and even better than his own Solo. In SW you're never too sure if the actors just really suck, or if it's tongue-in-cheeck B-movie acting. In Indy, you don't even wonder, it's clearly a stylistic choice. The only thing Indy failed at was to create a new Darth Vader that stood out enough to become iconic.). The comic book characters were part of the movie's charm. Indy at the time was the perfect cool. unpretentious and fun movie. Having iditiotic, over the top cardboard villains was even a plus in those years, whether the iconic DV type in SW, or the Nazi idiots in Raiders - (a long, and even better, a clearly defeated enemy to caricature was really perfect for the time. We only had to turn on the news to see real and invented villains that none expect to be able to defeat any time soon, and plenty of realistic movies with realistic villains to choose from. I think Indy became a "classic" very much because of this initial impact. It's not all that great objectively, but it as one of the movie for its time, and it marked people a lot for the initial fun we had watching it, and it has endured. But originally, a lot of the fun had evaporated by the time the second movie came out (it was succesful, but not nearly the event the first one was, which itself was nowhere as big an event as SW and ESB but still one).