We need ruthless board
This season, Chelsea have won their fifth Premier League title since Abramovich went to the Blues. That's more than Arsenal under Wenger who was at Arsenal longer than Abramovich at Chelsea.
When Arsenal had David Dein to threaten Wenger, Arsenal was very successful. We were able to win three titles, go 49games undefeated, and even got the Champions League semi-final.
Arsenal was never the same once Dein left in 2007. We got Kroenke in 2011 who only cared about the club because Wenger was great at making a profit. He was only there to make a profit and valued that over success. He was never a threat to Wenger which allowed Wenger to become really stubborn in using the same formation all the time and never buying key players that would have won us the title and still keeping his job.
Kroenke doesn't know a lot about the sport, to be honest, but he could threaten Wenger to make some key changes to end our title drought. Instead, he just sits back and let the cash come rolling in.
If we really want to win like Chelsea, we need a threatening board who will sack the manager if necessary to be successful.
Other Examples: Leicester, Man Utd., Real Madrid, Dortmund, etc.