The U.S. lost to a Nigeria team with just seven NBA players (Shoutout to the Diaspora), then followed that up with a loss to an Australian roster with just six NBA players. They are just exhibition games, and a high level of concern may be an exaggeration, but when you start accomplishing negative feats for the first time in 29 years, that concern is warranted.
Saying years in Olympic Basketball is a bit misleading, considering the games come every four years. But even then, the U.S. has only not won gold once since they started playing pro players seven tournaments ago in 1992. The U.S. finished with a bronze medal in 2004, with a leadership-lacking roster where 8 of the 12 players were 24-years-old or younger. And while this current roster is not nearly as young, an important factor is that there seems to be a lack of leadership with this team, as there was in 2004.
Experience should not be confused with leadership. While this team has plenty of experience with Kevin Durant and Draymond Green returning as Olympic champions, there is still a leadership issue.