Why do we assume Mbappe will join Real Madrid? Despite his desire to play there, would La Liga be as exciting without Messi and Ronaldo every week? He has proved that he is determined to win the Champions League, which PSG, even with Neymar, Messi, and himself, couldnt achieve. Still, thinking about him playing in the EPL, where the competition is stiff and the weather is so different from Parisian nights, makes me laugh.
Regardless of anyone's assumptions about this, if Mbappe wants to win titles in the domestic league and Champions League next season. So Real Madrid is the more appropriate team for him in that regard, even though other teams are also more appropriate, such as several teams in the EPL. However, considering the competition and the very different weather as you said, the consideration might be quite correct if Mbappe wants to choose Real Madrid as the team that will make his career even more brilliant than it is now.