Superman is nothing more than a heartless cad. He lets so many people die. Think about it. There’s is always going to be someone who needs saving. There is always someone falling off a cliff or being kidnapped or crashing in a plane or diving off the Golden Gate Bridge, etc. 24/7. He must know that if he stops to rest for even a second, there go a couple hundred lives at least. But he does it anyway. Punk.
Hey, he never made any money, saving the world from Solomon Grundy. How smart is that? I mean, after the first or second time, you or I might think of looking into compensation for our time and effort in world-rescue work. But Superman? doesn’t even ask for a clean phonebooth to change in. tsk.
See, the Superman needing money thing never did anything for me. I figure that all he needed to do was fly over the ocean, use his x-ray vision and find the Atocha or something similar, and he’d be set for life. Then there’s the whole “squeezing coal into diamonds” thing as well. Hell, the man can create wealth on a whim. Why does he need anyone elses money?
Other Superman money making schemes, if he had the need;
Lifting satellites into orbit.
Retrieving said satellites for repair.
Using his frickin’ laser beam eyes to perform large cutting/salvage jobs.
Super speed mine shaft creation.
Nuclear waste disposal (“Here, throw this cask into the sun”)
Heavy equipment moving.
And then like others said, there’s always someone needing to be saved. Why does he waste his time on petty thieves? Why is he busting up some back alley mugger when people are dying? The answer can only be Superdickery. 
He lives to make normal mortals feel insignificant, but of course, it would be bad PR to be too up front about that.
Granted, he really only has a job and secret identity for story purposes. (Maybe he does need human contact, but as a casual comic follower I’ve never felt he had many emotional needs.) But the diamond thing would deflate the price of diamonds if he did it in any significant amount, and also raise the price of coal by knocking down the supply, so…
Diamonds would be for amateurs. A year or two ago, there was a news story about a couple who came across this substance on a beach that turned out to be from whale vomit AND a key ingredient in the finest perfumes. Really. No doubt Superman could use his powers to get whales to barf up. He’d make more money than Bill Gates with that stuff.
While letting people die while he’s busy with that. Punk.
Precious ambergris?
THAT’S the stuff. I’ll bet Superman could rumble lots of ambergris out of whale’s bellies. The aforementioned couple got a lot of money just for their small find.
During the Silver Age, Superman routinely just used his X-Ray vision to dig up some old buried or sunken pirate treasure whenever he needed money.
I’m not kidding; he did this all the time. Apparently pirates in the silver age DCU buried the shit out of their treasure.
Post-Crisis, Clark Kent is a writer for one of the world’s premire newspapers and was, for a time, its editor-in-chief. He’s also had at least one book published (I want to say two).
I’ve seen fans work it all out before, and post-Crisis Clark is easily a millionaire.
If it were me, if I were Superman, I guess I have to admit I’d find it much more amusing to make whales throw up than to find buried treasure.
Tangent, but it always bugged me that Peter Parker was perpetually strapped for cash. With his abilities, he could easily qualify for a full athletic scholarship from any major university while continuing to study biochemistry, then play one or two years in the pros and, with proper investment, easily cover his and his sick aunt’s expenses for life. That’s the responsible thing to do.
Anyway, Clark Kent as a reporter was justified in Action #1 as satisfying the need to hear early on about crimes and disasters, at a time when a wire service was about as fast as the media got. Nowadays, he could just watch CNN or the Weather Network.
Sure, if you were a dick.
But that would be cheating! Unfair advantage! And think of his poor aunty!
Well, I wouldn’t want to hurt them. 
See? Now we come to the crux of it.
Superman can’t be all that bright if he continues to work as a reporter when he could live the Billionaire Lifestyle. Then he’d have all the time he needed to save people without having to find excuses to miss work all the time.
Wouldn’t that piss off Bruce Wayne!
“I’m still richer than you, Clark”
“Sure, today. But you got most of that from your father, not from your own hard work. And I still have three more Spanish Galleons and an entire Chinese Treasure Fleet that I know the whereabouts of. I’m just waiting for the legal papers and a good cover story before I bring them up.”
“You suck”
“Yup, stronger, faster, richer, smarter, better looking…”
“Dick!”
“Greyson? I thought he got tired of being your buttboy.”
“No, I meant you.”
Superman’s basically a god. He has access to Kryptonian tech a thousand years more advanced than anything on Earth. He only needs money as Clark, and as Clark he just needs enough to support the illusion that he’s not a god; in fact, Clark having tons of money is a BAD idea. (In the current storyline, Superman’s built a high-tech apartment for his “friends” the Lane-Kents, which strikes me as a bad idea secret ID wise no matter how convenient it is.) Kal is actually already rich beyond dreams of avarice; he just doesn’t care.
There have been some stories that tackle the question of why Superman doesn’t intervene in every single crime, feed all of the world’s hungry, or simply create wealth for everyone who needs it. Suffice to say that politics and economics are pretty formidable forces, and a powerful being like Superman can wind up causing more harm than good.
Superman doesn’t save everyone. He does THIS! {imagine Superman standing there with his hands on his hips, chest thrust out.}