The most important reason is Cousins has been suffering from injuries. Since he left the Kings, he has hardly been healthy, playing nonstop and playing less and less. Now he may have lost the feeling of controlling the game. Cousins is said to have hidden injuries in many places, which means that he may be out of action at any time due to injury. I believe that no team will want to sign a player who can't play football.
In addition, Cousins' current position is very unclear. Fans who often play ball know that, unlike playing wild ball, every player should have his own clear position in a regular game. After all, everyone has no strength like James and can do anything on the court.
For example, 3D players only need to defend and run, look for shooting opportunities, make decisive shots, don't do too many unnecessary actions, and don't think too much, so as to give full play to the maximum value of 3D players. Cousins is now faced with no clear positioning. Slow speed, unstable projection, and easy injury in internal confrontation. Moreover, in the era of small ball, the role of this center itself is not obvious, so that the team does not know how to use his remaining energy.
At the same time, there are players like Tucker in the free market, which are more attractive than Cousins. So far, no team is willing to sign Cousins. Finally, I wish Cousins can regain his strength and stand on the NBA stage again.