Nico William has a huge love for Athletic Bilbao. He has endured a lot of questions about his future. Being protected by the club, being attached to it since childhood, and having a brother playing are some factors that can keep Nico Williams in the Basque country longer. Nico Williams is not ready for the huge pressure of playing for big clubs, and staying at San Mames would be good for his career development. At the same time, perhaps his family and brother Inaki Williams also want him to stay in Bilbao for at least another year. Keeping Nico Williams is seen as a major turning point for Athletic Bilbao and the club's board ahead of the new season.
There is a better offer in the new contract that Nico Williams has so that makes him stay at Bilbao especially this is also a situation that could have been better because by being at Bilbao at least he does not have to think about competition for the line-up because he certainly already has his own place in the squad.
If it's not the real reason, why did Nico Williams stay in Bilbao? I think this is due to Barcelona's U-turn to buy Olmo instead of him. Remember that Barcelona is still struggling with their financial. And, they have not yet registered many of their players in La Liga due to the financial condition.
After Barcelona reported it, they approached Nico. But, they then decided to stop that and target Olmo instead. It's not due to the larger contract offered by Bilbao. However, Bilbao offered him a bigger contract, but you may not have the chance to join Barcelona again.
It makes Barcelona's offer is much more interesting than Bilbao, yet Nico has decided to stay.
He is still very young for now so there are still many opportunities to be at a big club later, even though in terms of statistics and strength Bilbao is still below some big clubs in La Liga but that should be an opportunity for Nico Williams to make him more interesting in the performance he does because if his consistency is maintained, sooner or later more big clubs will want his services.
As long as Nico can still consistently perform at this rate, he will always be targeted by the big clubs. Some big English clubs are linked to him, but there are no updates on the rumor.