And they’ll switch between sidewalk and road depending on the traffic, so I have no love for ebikers.
If they're switching between the sidewalk and the road, it's probably because they don't have even so much as a painted-off bike lane (not to mention a concrete-protected bike lane) to ride in.
That's not to say that some idiots aren't unsafe around pedestrians (I always slow down and always ring my bell when approaching people from behind, and I take extra caution around kids or pets), but the truth is that we always seem to have infrastructure for cars, we sometimes have infrastructure for pedestrians, but we almost never have proper infrastructure for biking or other forms of micromobility.
So next time you're irritated by a person on a bike, you might want to just take note of whether there is a safe, dedicated bike lane around or not, because in my experience it is very difficult to make a safe trip by bike where I life (in a very bike-friendly city, by the way) without sometimes taking or the road and other times taking to the sidewalk depending on what seems safer and less crowded. (Unless they're really trying to be unsafe and riding 20+mph on the sidewalk or something like that, then I'm with you, fuck em.)