Hilary got tons of coverage too and free advertisement for her. And Biden.They can bash Trump all they want, but they got him elected in the first place with all the free advertisement he was given during 2016. Even CNN and MSNBC aired several of his rallies without any commentary whatsoever.
You're correct that many news outlets are in business purely for profit, but that only reinforces what I stated: they're in support of the corporate status quo. If they stray too far from that, they lose sponsors and advertising.
Bernie Sanders is just not out there so there’s no juicy story they can get out of him. But Trump is an easy target for that. Or Biden’s scandals. They love scandals. And all the memes that come from it.