PSG is a very strong club financially but no matter how financially strong PSG is, they never want to lose money on player transfers. If a player moves to another club, the fee PSG receives for the player's transfer is a profit and PSG will never give it up. PSG spend huge amount of money to buy world class stars but due to their main focus on only world class stars they forget that world class attacking line up needs world class defense and midfield line up. If they hadn't forgotten this, they would never have bought world-class stars, they would have bought world-class stars and quality midfielders and defenders to make them a complete team. PSG is a team that has always failed in this perfection.
I agree with you but it is totally normal. I think none of the richest teams would like to lose a lot of money in transfers. This is why they are trying their best to keep Mbappe for one more season now. Mbappe's being sold in the previous transfer window was their priority. Because he wasn't keen on signing a contract extension.
However Mbappe just wants to stay for his last season with PSG and then leave. Otherwise PSG would have still made a serious profit in his transfer to Al-Hilal. PSG signed him for a record price back then and I understand them about not wanting to lose him for free.
Mbappe will stay at PSG for one more season. And will leave the team as a free agent. Perhaps this is his main goal. If he leaves the team as a free agent, he can get a large signing money from his future team. Mbappe will benefit from this. PSG also offers high wages. However, if a player like Mbappe leaves the team as a free agent, PSG club will not benefit. PSG management could have made a huge amount of money by selling Mbappe.
Both Mbappe and PSG would have benefited financially if Mbappe went to AL Hilal for 1 year. I heard that AL Hilal club, for Mbappe, was ready to spend 1 billion dollars in 1 year. However, Mbappe was not interested in going to Saudi. Mbappe is most likely to be seen in a Real Madrid jersey next season. Also, Mbappe extending his contract with PSG is no surprise. Nothing can be said for sure about Mbappe's transfer.