I am often contacted by clients claiming that they have been studying Japanese for about a year and still can’t read a manga or understand anime. When I tell them it’s perfectly normal, they are surprised.
Beginner learners are not aware of the time they will need to spend to learn Japanese. After an initial burst of motivation, they soon find themselves struggling more than expected. Of course, that has nothing to do with any individual trait. It simply takes a really long time to learn to handle Japanese skilfully.