As a 4runner automatic transmission dipstick expert (I have removed mine a whole two times), I can tell you I have never had mine go in easy. I also think mine is a little bent from someone who used it in the past.
Seems like there is a specific direction that it goes in a little farther than the other, and after that you have to push it in with a little force, holding a couple inches above the dipstick tube at a time. Not enough force that you're bending it though.
It would be nice to know if this is the wrong way, but I haven't found any better way to do it.
Putting hair on it helps too.