Ending 5% makes the starting 95% wasted time

Rating: 2/10 (17 January 2017)

So this review has spoilers. If you haven't seen the movie, the only continue reading if you don't care for spoilers.
So the start of this movie, up till 95% was absolutely awesome. I was hoping for the sweet revenge of DiCaprio totally taking down this institution.
However he last 5% of the movie shows that he was dreaming/imagining up ALL of it. All the 95% was his frickin imagination!!!! Oh my gosh at that point I felt like I had wasted HOURS of my life. The first 95% of the movie likse 2+ hours. I know movies aren't real, but now the STORY WASN'T REAL. I watched the movie for the story, just to find out in the ending that everything up to that point was not real story, just imagination of the patient. What on earth?!? If the ending was where DiCaprio got revenge on the institution, then this would be mind blowing 10 on 10 review for me!