If you think about it the very country itself is a ibn Saud mega project. I mean the current king is only the son of the founder of Saudi Arabia. Before they discovered oil in the 1920s the country didn't have anything more sophisticated than mud huts or the occasional palace/mosque that would fit in fine in the 16th century.

To basically accomplish going from goat herders in mud huts to sky scrapes and global relevancy in a single monarstic generation would inflate the egos of any family.

I'm not saying that they will succeed, but I am saying that you didn't count all the mega projects they actually succeed in such as building multiple modern cities in the desert and they did so within a generation.