Sadly, there is no cure for megalomania. But venture capitalists ought to start funding the search for a cure, because it's costing many of them a lot of money, and is likely to cost even more in the future.

Here's how it works. A smart entrepreneur – a Harvard dropout, say, or some guy who made a lot of money by selling off his last venture to some clueless multinational – starts up a web business which grows like crazy by attracting millions of subscribers who use its services for free. Pretty soon, it's got 400 million of them and everyone is saying: "Wow! 400 million users! That must be good for something."

Then several things happen. Firstly, the proprietor of the sensation du jour starts drinking the Kool-Aid and contracts the aforementioned megalomania. He begins to fantasise that he could own the whole internet. Secondly, thousands of other entrepreneurs think "Wow! He could own the whole internet. We need to make sure our stuff has hooks into his stuff. Otherwise, we're toast." And then the mainstream media, whose insights into this could be written in 96-point Helvetica bold on the back of a postage stamp, are going around saying, "Jeez, this stuff is the real deal. How do we get onside?"

The Facebook phenomenon provides a perfect illustration of this process. At the moment, it looks like an all-conquering monster, and is being reported accordingly. According to conventional wisdom, if the last decade was dominated by Google, this coming decade will belong to Facebook. And the company is beginning to behave as though it believed this.

On 21 April, Facebook's CEO, Mark Zuckerberg, announced some moves aimed at consolidating Facebook's supposed grip on the web. From now on, for example, visitors to an increasing number of high-profile websites will find a "Like" button on the page. Click on it and the news that you approve of the site's content will automatically be integrated into your Facebook profile, for the delectation of your friends. (Interestingly, there's no "dislike" button, which tells you all you need to know about the motivation behind this technology).

This move caused jaws to drop all over the blogosphere. "I think Facebook just seized control of the internet," wrote one excited commentator. And Slate's technology writer, as he listened to Zuckerberg's presentation, tweeted that "Facebook is going to be everywhere. Facebook is basically going to be the web."

Meanwhile, over at Spotify, the wildly successful music streaming service, they've also been making big changes. On 27 April they announced a major upgrade to their service. Among the new features is – yes, you guessed it – Facebook "connectivity". All your friends who are using Spotify will appear on your screen, and you can drag and drop playlists to them. So now all your Facebook buddies will know you're partial to Status Quo, the soppier end of Norah Jones or Classic FM compilation albums. Or worse.

But that's just the cosying-up-to-Facebook end of it. Spotify's announcement also suggested that they, too, have been drinking the Kool-Aid. From now on, Spotify users will have a "library". This is a virtual container that holds any song in a Spotify playlist that you've saved, any MP3 files on your hard drive and any songs or albums that you've "starred" as favourites. Henceforth, Spotify can search any folder on your computer for audio content and play it just like a stream from the web, or like iTunes does with your offline library of songs.

What that means, in the words of one commentator "is that you can now use Spotify to entirely replace iTunes, Windows Media Player, Winamp or any other music playback software on your computer. It can even sync local files wirelessly to an iPhone, if you're a Spotify Premium subscriber, and support for Android handsets is promised soon". Translation: Spotify will be the Only Thing You'll Ever Need – the solution to all your problems. Megalomania rules OK.

What's comical about this stuff is not so much its implicit arrogance – the assumption that we all want to share using Facebook – as its historical naivety. The history of the web is littered with the whitened bones of enterprises that once dreamed of total control. So until the cure for megalomania is invented, the only known antidote is a mantra. Repeat after me: the net is bigger than any single enterprise. And nobody owns it.