Why the ending of the movie The Truman Show was shocking

(1)This world is all lies and deceitful
(2)There’s nothing to be afraid of in the world I built
(3)You can’t leave
(4)Let’s do it in advance since we might not be able to see it
(5)Good afternoon. Good evening
(6)In fact, the Truman Show was a real thing where machines were the whole virtual world Frozen Logram and many humans believed that the Truman Show was an imaginary truth alien and were kept by machines
(7)the set-up that there is