from what I see, benfica is playing well and has been winning games without E. fernandes, so this is a situation in which benfica profited as always, benfica is a team that is already well prepared to adapt when a player is sold, that's because they are used to buying cheap players and selling for a very high price and making a profit
Did people too over estimate the talent of Enzo Fernandez?
He did not have too many matches for Benfica and in Europe. The performance with Argentina in World Cup 2022 brought him to the spot light and a chance to move to Chelsea with very expensive transfer price. Lessons learned from many big transfers as consequences for World Cup or Euro tournaments. Many of rising star players from big tournaments failed after one to three seasons. They are not talented enough or bad to cope with pressure from expensive transfers.
they have been in this business for years, winning the Portuguese league and just for the sake of reputation and access to the champions league, but they already have the business of selling of players that gives them good profit
Benfica is like Sevilla in La Liga. They are growing from average clubs to top clubs in their leagues and join tier-2 clubs in Europe. They have similar growth strategy by building up good scout teams to hunt for youth talented players. Then buy those youth players with cheap prices and give them chances to play in their leagues. If those youth players succeed to grow up, they sell those players and get good money for their clubs.
In Portuguese league, Porto is another club that has similar transfer strategy like Benfica.