So.. for 'them' to use your 'data' in the fashion you're afraid of, the following has to be the case: You're high profile enough for them to care, and you're high profile enough for other people to care. You have to have something that isn't illegal going on (because then you'd just be prosecuted) that you don't want anyone to know, which there are electronic records to prove. You have to value that aspect of your privacy above whatever cause makes you important enough to target, and it would also have to be bad enough that it would override whatever your cause was in the eyes of people that likely already support that cause.
Alongside that, it requires shadowy, nefarious behaviour by those designated, notionally, to uphold the law, that could be assumed will generally act legally, though perhaps not ethically or morally. In spite of this, corporations that you are most likely using voluntarily are a problem because they may pass your 'data' to the government... and this all happens while the digital surveillance may also, probably more often, be used to track down and prosecute actual criminals, or prevent actual crimes.
Now, I'd agree such behaviour could be fairly deplorable, though with two main observations. Firstly, though deplorable, the behaviour is not the default outcome of digital surveillance, but more the effect of allowing deplorable people to use it (in the same way that 'Guns don't kill people, people kill people'). Secondly, this scenario doesn't apply to a lot of people - as a tactic it may be difficult to effectively deploy, and may not even be reliable as the population can't be assumed to react in a predictable fashion, or even at all.
What may or may not be much easier to deploy, depending on a countries governmental structure (i.e. where a person lives), is simply passing political isolation laws that severely limit freedom of association, freedom of expression and freedom of assembly with a view to stifling opposition to the government, and since these things become enshrined in law they affect EVERYONE and ANYONE (that is actually subject to the law) - this can be done in plain sight, it doesn't require clandestine actions by nefarious actors... in an autocratic regime it just gets passed in to law. Opposition is made illegal, simple as that - no international playbook required.
... I'm obviously referring to Bahrain here, but with Bills in the UK being introduced such as the Public Order Act, and the Police, Crime and Sentencing Act I'm not going to pretend we're immune from this attempted erosion of our basic rights either.
That's not to say that we shouldn't be mindful of our digital footprint. Whilst the first paragraph applies only to those it applies to, actual criminals who will use anything, anytime they can, against anyone, anywhere, would also like to get your data - they will take your money if they can, and they will assume your identity if they can. Also, the media should be considered - they don't have the direct power of the judiciary, nor the legislature, but them having your data could result in some of the things you suggest, i.e. manipulation (although again, that's subject to you being guilty enough of anything in the eyes of enough people for anyone to care)...
So yes, definitely be careful with your data, just don't assume that it does anything to protect your rights or freedoms because if your government is nefarious enough to manipulate or blackmail you, they're probably able to just take those rights and freedoms away anyway, with or without your actual data.