generalfrevious said:

Try watching American Graffiti or THX 1138 again; neither has aged well at all.

I don't know, I thought American Graffiti was really good. I think he really was talented at one point and had tremendous potential. Coppola said it, Irvin Kershner said it. George Lucas three 1970s films were completely different than the Star Wars prequels, there's just no getting around it.

I think a lot of it has to do with pride and starting to believe his own hype that he was a genius. He is talented, but before his personality changed he listened to other peoples' advice:

1977:

https://www.youtube.com/watch?v=AnqdrnT5q7c

1983:

https://www.youtube.com/watch?v=ykmZp5cgbkU

1995:

https://www.youtube.com/watch?v=FCzGerUThSg

2007:

https://www.youtube.com/watch?v=v94Tb8RN84U

2012:

http://www.youtube.com/watch?v=KM5VECv5Y6A

walking_carpet said:

All filmmakers have a portfolio with peaks and valleys and maybe a decline towards the very end. But you do not have the outrageous dropoff from the OT (and ROTLA) to what we see now unless something else was at play.

I think his personality just changed.