Just like many other players, Benzem chose money and he joined Arabian teams when left he is getting old to earn more money there.
I think Benzema made a wise move and Real Madrid should now hire an alternative player for this position. Mbappe is the first priority and I guess Mbappe can fill Benzema's position at Real Madrid perfectly.
If Mbappe's transfer to Real Madrid takes place, a football player who will play successfully for many years as Real Madrid Benzema will be brought to the team. I believe Mbappe will outperform Benzema. What he's done for PSG is obvious and he's a perfect player statistically.
Karim Benzema's decision chose money over playing in Europe is the best decision he cane make at this time and age of his football career and as a big fan of him, I'm very happy he made that decision. Benzema before leaving the French capital to join the Saudi Arabian club has achieved every possible achievement in club football with Real Madrid including winning a Balon D'or and that makes it a very wise decision to go for money in the last years of his playing career.
Kylian Mbappe is reportedly not happy in the French capital and it's speculated that his preferred destination is Real Madrid which I think will be the best replacement for Benzema