If academics and politics seem like separate fields to you, that’s because your definition of academics has been corrupted by the academicians you have seen and their self-centredness.
Academicians can be of two types. The ones who “care only about science (or “truth”)”. The ones who care about society in addition to science.
Those who “care only about science” also care for something besides science. They care for themselves. They care for their own intellectual satisfactions or humane curiosities.
So, academicians can be of two types. Those who care only about themselves, and those who care about society too. (Of course, it is a fluid spectrum. At any point one can care x% about themselves and y% about the society. I’m using a strict binary for convenience.)
The academicians who care predominantly about society automatically engage in politics. Because that’s the only way to change the society. Like I wrote about earlier, politics isn’t just party politics. Politics also includes advocacy, activism. Academicians, by asking the right questions and “generating evidence”, influence policy making and politics. They can give legitimacy to certain questions that go unasked. They can strengthen or weaken anyone’s politics.
So what’s the difference between a politician and an academic in politics?
Their willingness to lie.
An academic who is willing to lie for their politics is a politician. No matter how much they are in politics, an academic who will not lie for their politics is still an academic.