Players come and go, unfortunately there are no longer any flags and there are no longer any important players who give everything for the club and for the shirt, they take advantage of themselves and go to clubs where they get paid more, the world has changed and this has also had repercussions in football, when a proposal is made the players leave, there is nothing left to do.
You just defined modern football in simple terms which is money. The problem we have now in football is the loss of passion for the game, football to me now is very much different to what it was back the , you would see players who are so passionate about the game and the club they represent, they fight for the club badge back then these days it's not the same thing, players are all about the money, looking for the club that bids the highest for them to join and not joining because they have love or passion for the club.
I would also add one big difference compared to the past: clubs rely always more and more on foreign players because, in many cases, they are cheaper. This creates a chain effect because usually big clubs buy players from smaller clubs, but if these smaller clubs are full of foreigners, they have to buy foreigners. And what does it mean? That these players have no connection with the county and the club(s), they will simply go where they are paid more.
I'm Italian, I remember players such as Del Piero, Maldini and Totti, just to mention a few: those are players who received offers from all the biggest European team, even offering them way more money than what they were making, but they always refused because they loved their clubs. These kind of players now don't exist anymore.