Firstly, having kept up for administrative activities for all these administrations, I always said most needed to be impeached.
They got away with ignoring laws because they felt safe from impeachment. Making this threat real is probably for the best.
But secondly, both Trump and Biden were impeached or face impeachment because they did (at least) sketchy stuff.
If future presidents knock that off it's reasonable to believe they won't be impeached.
These two are just awful. I'm not saying equally awful, mind you, but each awful in their own way.