Financially Atletico absolutely are minnows.
Do some research on their finances and the rest if La Liga's. It's an absolutely mess outside of the duopoly.
Again, Atletico have earned enough money in the last 3 years, EL winners, CL finalists, La Liga winners, CL regulars now.
But anyway, go on: Why in your opinion is Koke then still at the minnow's Atletico despite interest of two giants like Barca and United? Then he was al´so linked to Bayern Munich but the rumoured interest was not as strong as from Barca/United as far as I could follow.
He is currently at his boyhood club, living in a city like Madrid, winning stuff regularly, increasing his salary every 6-8 months (who knows, maybe he also gets a signing on fee or similar things every time he extends). In addition only recently they have got this Chinese guy who bought 20 % stake in the club.
You need to consider how Atletico work and not how United / Madrid works and then just transform it to Atletico. United / Madrid have ridiculous revenues but then they also have 30 mil players sitting on the bench earning a fortune. Atletico aren't close to that kind of revenue but then they are also not close to having expensive transfers on the bench or high earning squad players. Their squad is paper thin and they have a very clear first 11 most of the time without much rotation. This way they can focus to give their regulars most of the money and have squad players on relatively low wages. Yes, they sell 1 or 2 players every summer, but they don't need to for now, they didn't force Costa to leave for example.
It's not strange at all that Koke might value (just as an example) "6 mil salary + his boyhood club where he is settled and loved / his gf and family are settled + the city Madrid and then Spain in general" higher than "a big European club + 10 mil salary".
Money is important as everyone knows, but not equally important to everyone especially compared to some other aspects (it's always a combination package).
Because for every Götze or Kroos there is a Hummels, Godin or even our own Scholes who was never the highest earner at United and could have signed a blank check at Inter but didn't even consider it.