Dehaye says he knows this because he has taken them all on and paid a personal and professional price.
Since the Facebook–Cambridge Analytica scandal broke after claims the US social media giant had improperly shared the data of nearly 90 million users with the UK political consultancy, Dehaye has been a man in demand.
Last week he spoke in the UK parliament about the issue, while business magazine The Economist recently related Dehaye's lengthy and convoluted attempts to access private data Facebook held about him via an advertising tool called Pixel.
But it hasn't always been like this. For a long time, no one wanted to know him.
“I have made mistakes. The biggest one was to go it alone. Without allies you can't win these sorts of conflicts,” Dehaye told Swiss daily Tages Anzeiger on Wednesday, referring to his long-running disputes with companies over their use of his personal data.
The former Stanford student, originally from Belgium, has long been interested in the issue of data trading, but it wasn't until he took on the role of assistant professor in mathematics at the University of Zurich in 2012 that he saw first-hand how the business worked.
The university had teamed up with California-based Coursera, which in 2013 had 83 partner universities to which it supplied – ostensibly for free – an ecosystem including chatrooms and videos.
But when Dehaye started to question how the personal data being collected by Coursera was being used, and what the impact of all this data flowing to the US might mean for future generations, university professors and lawyers he consulted showed little interest in upsetting the tech apple cart.
He then upped the stakes, creating a course on the Coursera platform examining the business model of these types of education intermediaries. This won him attention: the Californian company filed a complaint about him and blocked his accounts so he could no longer communicate with students.
The university also launched an investigation against Dehaye who says he was then cast as a troublemaker by the institution. He suffered a “burn out” and moved to Geneva.
Then in 2015, the mathematician stumbled across an article in UK daily The Guardian about a British firm that specialised in psychological profiling and was then being used by US senator Ted Cruz: Cambridge Analytica.
Given his experience with Coursera, the alarm bells went off. Concerned about the impact of a British firm using the private data of millions of Americans without their knowledge, he jointly investigated the company with journalists from the Tages Anzeiger, with the resulting article highlighting the dangers posed by the firm appearing in December 2016.
That article argued that Cambridge Analytica was behind both Donald Trump's online election campaign and the successful Brexit campaign.
It also outlined the concerns of former Cambridge university researcher Michal Kosinski about a mysterious firm called Strategic Communication Laboratories (SCL) which was trying to purchase data obtained via his team's Facebook-linked MyPersonality psychology app for reasons it would not reveal.
A spin-off company of SCL was later created: Cambridge Analytica.
Paul-Olivier Dehaye shrugs off talk of “mindless zombies” being influenced by Cambridge Analytica to vote for Donald Trump.
“The question is not how individuals can be influenced. The question is what influence this type of manipulation has on the whole network and on information flows in the network,” he says, adding that it is difficult to find people who will change candidates but that psychometric data is very useful when it comes to identifying people who will share information, or false information, on the network.
Dehaye has now cofounded a start-up helping people to control private data held about them by companies.