The tech press is full of people who want to tell you how completely awesome life is going to be when everything moves to "the cloud" – that is, when all your important storage, processing and other needs are handled by vast, professionally managed data-centres.

Here's something you won't see mentioned, though: the main attraction of the cloud to investors and entrepreneurs is the idea of making money from you, on a recurring, perpetual basis, for something you currently get for a flat rate or for free without having to give up the money or privacy that cloud companies hope to leverage into fortunes.

Since the rise of the commercial, civilian internet, investors have dreamed of a return to the high-profitability monopoly telecoms world that the hyper-competitive net annihilated. Investors loved its pay-per-minute model, a model that charged extra for every single "service," including trivialities such as Caller ID – remember when you had to pay extra to find out who was calling you? Imagine if your ISP tried to charge you for seeing the "FROM" line on your emails before you opened them! Minitel, AOL, MSN — these all shared the model, and had an iPhone-like monopoly over who could provide services on their networks, and what those service-providers would have to pay to supply these services to you, the user.

But with the rise of the net – the public internet, on which anyone could create a new service, protocol or application – there was always someone ready to eat into this profitable little conspiracy. The first online services charged you for every email you sent or received. The next generation kicked their asses by offering email flat-rate. Bit by bit, the competition killed the meter running on your network session, the meter that turned over every time you clicked the mouse. Cloud services can reverse that, at least in part. Rather than buying a hard-drive once and paying nothing – apart from the electricity bill – to run it, you can buy cloud storage and pay for those sectors every month. Rather than buying a high-powered CPU and computing on that, you can move your computing needs to the cloud and pay for every cycle you eat.

Now, this makes sense for some limited applications. If you're supplying a service to the public, having a cloud's worth of on-demand storage and hosting is great news. Many companies, such as Twitter, have found that it's more cost-effective to buy barrel-loads of storage, bandwidth and computation from distant hosting companies than it would be to buy their own servers and racks at a data-centre. And if you're doing supercomputing applications, then tapping into the high-performance computing grid run by the world's physics centres is a good trick.

But for the average punter, cloud computing is – to say the least – oversold. Network access remains slower, more expensive, and less reliable than hard drives and CPUs. Your access to the net grows more and more fraught each day, as entertainment companies, spyware creeps, botnet crooks, snooping coppers and shameless bosses arrogate to themselves the right to spy on, tamper with or terminate your access to the net.

Alas, this situation isn't likely to change any time soon. Going into the hard-drive business or the computer business isn't cheap by any means – even with a "cloud" of Chinese manufacturers who'll build to your spec – but it's vastly cheaper than it is to start an ISP. Running a wire into the cellar of every house in an entire nation is a big job, and that's why you're lucky if your local market sports two or three competing ISPs, and why you can buy 30 kinds of hard drive on Amazon. It's inconceivable to me that network access will ever overtake CPU or hard-drive for cost, reliability and performance. Today, you can buy a terabyte of storage for £57. Unless you're recording hundreds of hours' worth of telly, you'd be hard-pressed to fill such a drive.

Likewise, you can buy a no-name quad-core PC with the aforementioned terabyte disc for £348. This machine will compute all the spreadsheets you ever need to tot up without breaking a sweat.

It's easy to think of some extremely specialised collaborative environments that benefit from cloud computing– we used a Google spreadsheet to plan our wedding list and a Google calendar to coordinate with my parents in Canada – but if you were designing these applications to provide maximum utility for their users (instead of maximum business-model for their developers), they'd just be a place where encrypted bits of state information was held for periodic access by powerful PCs that did the bulk of their calculations locally.

That's how I use Amazon's S3 cloud storage: not as an unreliable and slow hard drive, but as a store for encrypted backups of my critical files, which are written to S3 using the JungleDisk tool. This is cheaper and better than anything I could do for myself by way of offsite secure backup, but I'm not going to be working off S3 any time soon.