Atletico Madrid are not too rich like Real Madrid and Barcelona but remember that in the last two decades, they are the only club that won La Liga title and they won two titles with Diego Simeone. It's very impressive if we know that last two decades are dominating years of Barcelona and Real Madrid with Messi and Ronaldo.
In this season, Atletico Madrid have very good performances and now they have very good rank, that opens their good chance of competing La Liga title. Athletic Bilbao will have to accept their fourth position as they are not good and experienced enough to win La Liga title. To win it, they must win not only Atletico Madrid but also two other strong competitors Real Madrid and Barcelona, it's impossible.
Barcelona has also been experiencing financial difficulties in several seasons so their position with Atletico Madrid is not too different, it's just that Barcelona has much better academy players so they can solve financial problems. Atletico Madrid is still quite favored to compete for the title this season even though Barcelona is much better prepared but there are still many things that might happen in the remaining matches.
The title race is still uncertain at this time because the three teams have a number of points that are not that far apart so that the chances for all three are still quite open. For Athletic Bilbao itself, it will not be able to compete with the three top teams because they do not have the ability to compete and all they can maintain is the top four position if they continue to be consistent.