You could quite easily build a business around comic books if you had enough knowledge of the industry. Books can be rare and valuable and in many cases not too rare and still worth a bit of money due to the author or artist signing the book (I've had Spiderman's creator sign multiple original copies of Amazing Spiderman one and let me tell you, that adds significant value!).
You could get into the world of comic book based niches such as action figures, statues and other high end collectibles
Another great way to make money with comic books is to buy and sell original art. I have a few pieces of original art, but it isn't a focus for my collection. Again, signatures (particularly if they can be verified with a picture of the creator signing) add value but you don't have to go for something incredibly expensive if you just want to be in the hobby for pleasure instead of business. I have a relatively low value piece which was published in the late 80's or early 90's. It's a page of a Spiderman comic that was actually used to produce the issue that month. Very cool, but I was also able to get the artist to sign it to me when I had worked the deal out with him (in this case, unless I'm going to sell it to someone named Jim I stand a lower chance on making a profit from this piece- but that isn't why I bought it).
So long story short; you can collect comics for fun or for profit and either will serve you well.