They had all these visions of grandeur that Facebook could plug various services to their existing users and make endless amounts of money. Maybe add a Facebook classified ads service, document sharing service, auction site, shopping e-store for its members that takes a small commission. Whatever other companies did, just copy it and add it on Facebook and watch users instantly abandon competitors. After all FB has close to a billion users. Little did they know that Facebook users were never that engaged nor will they ever be.
The collective hive mind of bored humans completely ignored Facebook Questions. Zuckerberg's first attempt at trying to cultivate its legion of human potatoes. He quickly pulled FB Questions after no one used it and tried again later by changing it to Ask Questions and shoving it right after the "Add Photo/Video" link above the status update box itself. People are still ignoring it. Its members are there to share photos and talk to friends, not seek knowledge, not sell photos, not start businesses, not buy digital products, not share documents, or anything else productive or profitable for that matter.
In general users follow the "One website per one purpose" rule. Auction site neanderthal, eBay learned that the hard way when it simply tried to tack on classified ads thinking its members would ditch craigslist. Even monopolistic cro-magnon Microsoft has tried and failed numerous times at getting its installed base to use more profitable tacked on services and products. Ironically they only succeeded in spreading the worst internet browser in human history this way. Facebook's still in denial about it's useless network of potatoes. Sorry. Humans.
After all these years Silicon Valley still values massive droves of bored users without problems over clusters of customers with money in hand. In some ways they're right, Facebook still makes massive amounts of ad revenue and is still profitable. But I doubt it'll experience any further population boom or miraculous revenue growth.
The company isn't going anywhere for now, but as Facebook fatigue sets in and members find new and easier ways to share photos with friends (a user's main activity) things might not always be "flowers and sunshine" for FB. And in the future we'll look back in hindsight and say "I can't believe they didn't foresee it, all the signs were there."