@Infamouspixie70 read again: He never says "stole my friends" (cause he technically had none), he says "stole everything that was supposed to be mine", however, think about it again, why did Amemiya got the extra cheats? Did he tell Rodcorte "give me that guy's thing too"?
The one who did wrong was Rodcorte, Amemiya got everything but it wasn't like he even knew that it was from someone else, the MC was the last one to remain, nobody else could have known that he was forgotten. MC was hot blooded for sure at the moment he died, but if you think about it properly, Amemiya is not the culprit, MC just couldn't think straight.