For whatever reason, its not seen as proper for footballers to just come out and tell the truth, which is that they want to make as much money as possible, just like most other people. So you hear a lot about wanting to win trophies and tradition at certain clubs but in the end the three most important considerations are wages, wages, and wages.* No offense to all you United fans, but if Griezmann's most important motivation was to win trophies - meaning the big five domestic leagues and the Champions League - he would be intent on joining Juventus, Barcelona, Bayern, PSG, or Real Madrid. The Premier League is too competitive at the top to expect any club to dominate domestically and English teams have been absolute shit in Europe for a long while now.
*"Wages" as a shorthand that also encompasses other financial considerations like image rights, bonuses, etc.