As the Harvard Law professor said in the film, The Paper Chase, "legal terms don't mean anything you want them to mean." Using a clause specifically written into the U.S. Constitution to remove a president with cause, isn't 'overthrowing a president.' If it was, every past impeachment was overthrowing a president, which is absurd on its face.
There are people who were calling for Trump's impeachment since 2017. Logic tells us that, that doesn't mean that he hasn't committed acts that are impeachable. It is crystal cleat that Trump withheld duly appropriated aid meant for Ukraine, for the purpose of pressuring President Zelensky to launch a clearly phony investigation into Joe Biden, which would do nothing at all to help either Ukraine or the United States, but would work to Trump’s personal political benefit. Withholding the aid would have sabotaged Ukraine in its war against Russia, and even hinting at withholding the aid has harmed Ukraine’s negotiating position with Russia. So Trump has done public harm in an attempt to get private benefit. Yup, that's an impeachable offense.
Moreover, Trump has been doing everything that he can to starve the Congress of information needed for the impeachment investigation -- thus, trying to use obstruction of Congress as a means to sabotage the impeachment. That's impeachable too.