Can someone explain why people lose their minds at this on ramp?

So I take this exit from 405Nb to the 124th ave exit that merges onto 520Eb for work. It seems like every single day with out fail, someone in the 520 on ramp lane cuts over at the last second to take the 124th exit, almost taking my bumper off, then don’t take the 124th exit and drive onto 520??? I don’t get it?? Am I missing something?