Dystopian fiction – from Anthony Burgess’s A Clockwork Orange to Russell T Davies’s spectacular recent BBC1 series Years and Years – is usually intended to take elements of the present and then imagine a future in which they have become inescapable, so as to warn us of what might already be in our midst.

But the 21st century is challenging this technique in one bracing sense: the way the world now seems to race beyond the wildest aspects of our collective imagination before we have even started to think about what might come next. Consider last week’s news about Facebook, and the fact that three years of corporate disgrace – and rising noise from legislators about bringing the tech giant to heel – have yet to slow its terrifying quest to insinuate its workings into every area of our lives. Now, in a move that could have been taken from a futuristic novel, it wants to create nothing less than a new global currency.

“Libra” will be pegged to a basket of mainstream currencies at a value of about a dollar, and rooted in the model of secure, immutable online transactions we know as blockchain. Its operations will be overseen by a new organisation based in Geneva, open to any company or corporation that has a value of at least $1bn (£790m) and will invest a minimum of $10m. There are currently 28 such participants, ranging from Uber and Spotify to Mastercard – and by way of assuring sceptics of its supposedly hands-off intentions, Facebook insists its own voting power will be restricted to 1%. But Libra is a project conceived and developed by Mark Zuckerberg’s company. And the currency will only perform the necessary feat of scaling up if it becomes a central part of the lives of the billions of us who use Facebook’s platforms, via a linked app called Calibra that will initially be woven into Facebook Messenger and WhatsApp.

Naturally enough, the idea is presented not in terms of profit maximisation, but the philanthropic feelgoodery that seems to make northern Californians billionaires as a matter of accident. One element of the initiative is making person-to-person transactions possible at either low or no cost – so that the migrant worker, say, can wire money home to their family and be assured that no one will be taking a cut. Moreover, thanks to the ease of wage and bill payments, people so far left out of financial services can cease to be “unbanked”, and thereby gain more personal freedom. This is hardly a new idea, but, as with most Facebook initiatives, it’s superficially a very good one.

But, capitalism being capitalism, there are likely to be more venal motivations at work. There are vast markets in the developing world where Facebook and its subsidiaries have millions of users but are held back from creaming off advertising revenue by the simple matter of poverty. Libra offers new revenue opportunities, partly by inviting people to exchange national currencies for the new medium, thereby gifting Facebook and its partners a vast pool of funds. In these territories, and more affluent places, the new currency also offers Facebook the chance to accelerate what sits at the heart of everything it does: the harvesting of endless data, which can then be monetised.

Facebook is at pains to address such anxieties, but its initial outline of how the new currency will be used in Messenger and WhatsApp via Calibra is not exactly reassuring. At the very least, Facebook will know the people and companies with whom its users have financially interacted, but that is likely to only be the start. “Calibra will not share account information or financial data with Facebook, Inc or any third party without customer consent,” it says (my italics). Obviously, the company has past form here: the kind of forced consent that means you either allow Facebook to gobble up your data or don’t get access to many of its services. Whatever the guarantees, the most basic point is obvious enough: why should a company with such an appalling record on personal data be trusted to so massively extend its reach?

Other questions abound. What will happen if Libra sucks national currencies out of already vulnerable economies? What will be its relationship to inflation? What of the dangers of international money laundering? Why are Facebook high-ups already talking about Libra extending into credit?

Such concerns were highlighted last week by indications that India’s institutional hostility to cryptocurrencies means Libra will not be launched there, for the time being at least. But every bit as alarming is how the entry of Facebook into the creation of money will lead it to another sphere currently overseen by the state: beyond everyday consumerism, into the nitty-gritty of how we use public services and interact with government – in education, health, social care, crime and punishment, and everything else.

Google has already got there, as proved by everything from its vast presence in the US education system to the use of NHS data by its artificial intelligence wing, DeepMind. But think about everyday payments: come 2050, across the planet, what currencies do we think will be used for taxes, benefits, fines, bail, student loan repayments and all the rest – and what will happen to the huge data trails such things create? In China, those on the all-encompassing social network WeChat – which Zuckerberg clearly wants to emulate – can use it to pay taxes and fines. Even in fusty old Britain, the Cabinet Office has already considered using Facebook logins as a means for people to access social security benefits, make council tax payments and get a driver’s licence. Why would it not then think about what we may yet know as Librafication?

At that point, surveillance capitalism would colonise the shrinking parts of our lives it has so far left relatively untouched. It would amass mountains of lucrative information about everything from our friends to when we last paid a speeding fine – and in the process, bring unlimited corporate power into areas we still consider subject to the checks and balances of democracy. The state could also have a field day: can you imagine the glee at the Department for Work and Pensions if it was able to monitor not just people’s universal credit payments but how they spent them?

But the biggest question of all is screamingly obvious, and worth asking for the thousandth time: how, in any meaningful way, can we hold Facebook – and Google – to account, and drastically limit their power? The answer surely starts with a massive international no to big tech’s most hubristic scheme yet. Otherwise the creators of fictional dystopias may as well give up: however surreal and messed up their imaginings, the world will have gone beyond them.

• John Harris is a Guardian columnist