There is no point in trying to force him to stay. If he wants to go we just need to get the right price and try to spend it wisely. Keeping unsettled and unhappy players is not a lack of ambition.
If we had do what you say Gerrard would have never stayed, Suarez would have left a year early before becoming the best player in the league.
Top clubs don't sell their best players. It is their duty to persuade their top players to stay and attract new ones.