Lewandowski just moved to Barcelona and he is doing fine and can finish his career in Europe with a title in Barcelona and why not Ballon d'or. He might think later to join a team in Saudi Arabia or another rich league.
For Benzema, he played a lot in Real Madrid and with injuries and less time to play due to that, he better play more time in a lesser competitive league rather than wasting what left from his career.
For Modric, he is still fit and can find a suitable place everywhere in my opinion.
Robert Lewandowski has yet to collect one of the prestigious awards he has sought during his football career. I believe the only time he would have been rewarded with the Ballon d'Or was when they failed to observe the nomination for the irrevocable prize; yet, because this is football, we are still watching. Karim Benzema has already attained his highest football goals, and the Ballon d'Or increases his performances and reputation in the football world. Who can forget the last Ballon d'Or winner, Karim Benzema? Moving to Saudi Arabia was attractive because of the money; nevertheless, he needs to generate further wealth because, in the following three years, he will be seen as an old player nearing the end of his career.