I think it is very reasonable for Bilbao to want to keep the player while the club currently also wants impressive results at the end of the season with a very talented player like Nico Williams.
Yes, the player should have a lot of experience joining other big European clubs, but there is nothing wrong if Nico Williams tries to stay until 2026 near the end of his contract after that he decides to leave the club and chooses to join a big club to develop his career so that he is better known as a professional player.
it would be an advantage for bilbao to keep williams for now, looking at last season's la liga standings bilbao showed a satisfactory increase, and it seems that for this season bilbao's target is the top 4 in la liga, that would be possible and nico william can make it happen. moreover nico doesn't want to leave atletic bilbao for now, there are times when a player is reluctant to leave for a reason maybe that's what nico williams is currently experiencing,
seeing his young age there are still many opportunities for williams to develop a career as a professional footballer.