Is there just so much added pressure on teams to improve fans’/gamblers’ fantasy teams and sports betting outcomes? One related stat: “According to ESPN Stats & Information research, there have only been six NFL head coaches since the merger who didn’t finish their first season with their team, with three of those instances having come in the past three seasons: Urban Meyer (Jaguars), Nathaniel Hackett (Broncos) and Reich.“ https://www.espn.com/nfl/story/_/id/38991151/carolina-panthers-fire-head-coach-frank-reich
It’s more due to the fact that all the owners have significantly more money nowadays and are more willing to be aggressive with building a winning team. It has nothing to do with sports gambling besides that industry pumping more money into the sport to allow it.