Sports journalism is a profession where they can learn a lot of news and through various analyses they can collect and know all the information about different teams and players. By analyzing the information they have detailed knowledge about many positive and negative aspects of those teams. There may be some gamblers among them, but it would be foolish for them to expect any outcome of the game. Because you can gain a lot of knowledge about a team by analyzing its relationship and apply that knowledge while betting, but you should not think that the bet will go in your favour.
Journalists with the access to early developments like a managerial team member leaving the team unannounced, it's likely to affect the team's tempo in their next game. Let's say they quit the team on Wednesday while they face a match on Saturday. The journalists are the first to notice the information and would bet ahead of time and could share to friends their analysis considering a change that didn't make it to the mainstream.