The end-of-the-day betting effect doesn’t refer to something that occurs at the end of the day. It is a term used to describe the behaviour of some players as they are nearing the end of their gaming session.
This betting effect refers to players who tend to raise the stakes and bet more the closer they are to the end of their session in the hope of winning back some of the money they have lost.
There are several reasons for players wanting to end their session, such as being tired or having a low bankroll. Regardless of the reason, you should now understand what people mean when they say someone is under the end-of-the-day betting effect.