Demas deserted him, Alexander opposed him, Crescens and Titus weren't there when he needed them. The consequences of staying silent were too great. And sometimes, Paul's involvement in the gospel led him to political engagement in the secular world, in the Jewish politics of the ruling Sanhedrin, in the pagan politics of the silver trade supporting idolatry in Ephesus, in the political subtleties of being a Roman citizen in the lands beyond Rome. Paul was a canny strategist for the sake of the gospel. He was involved heart and soul, and because of this he shaped what the church would become.
Nothing is quite so inescapable or disillusioning as politics.
Politics is about power in relationships and groups. Every human relationship and group is therefore political by definition. You can be honest and intentional or dishonest and in denial but if you are alive you are involved in politics. Politics are not only a function of government, but of families, clubs, universities, sports teams, yes, even churches. And politics are always disillusioning because we do not always get our way, and sometimes the conflict itself does more damage than the goal is worth.