The thing is that many of those economic powerhouses managed to create hype just around their name, especially Manchester United. They made many see them as the biggest football club, just alone by marketing.
Real Madrid, Barcelona and Bayern Munich all been doing a excellent job there as well, but it takes time to reach those hights. Juve may not have the same financial power as those mentioned clubs and the likes of PSG and City, but youre model (along with Bayerns) are the sustainable imo. Also in Juventus like Bayern the team is the biggest player, not a single player. Offcourse both clubs have stars, but its more up to the team to create results and for that the clubs will always stand strong, even if a world class player leave.
Another thing that puts Juve a little back is the relative small stadium compared to the Man U, Real Madrid, Barcelona and Bayern. I really like Juventus Stadium (or should i say Allianz

), its quite cool. But the average attendance is way lower than the other clubs because of its small size. Before Juve build it bigger I doubt the club will catch fully up with the others as having a really big stadium is one of the most important factors when it comes to turning into a economic powerhouse football wise.
Else youre management are doing a great job overall. The idea of selling the star players needs to stop though as you cant rebuild every year if you have ambitions winning the CL. Keep the star players you have (reject selling Pogba, Sandro and so on), then add with good players here and there. It was the key for us winning the treble in 2013, you simply need to hold on to youre best players.
As much as i dislike Uli he is a strong man in that sense, if he wants a player to stay, then there is no chance for him to leave. Just my two cents about it