It goes very deep & there's a lot of angles to it but one way to put it is instant gratification by winning.
We as Humans enjoy instant gratification more than a long term one.
Most Lottery winners take the lump sum by doing so they lose a much higher percentage than take it over time keeping a significantly higher percentage.
I used to live 15 minutes from two different Casinos when I lived in Connecticut.
In a years time of living in Connecticut so close to both Casinos I went to both of them all together about 7 times with the exception of 2 times I was eating the marvelous buffet that they both have,
I gambled no more than $60 both times & it was mere fun, I was only there about 20 minutes each time.
It takes a lot of discipline to not keep putting money down when you go into those places & have money just in the elevator one time when I was eating at the buffet a couple was asking me if I won I said no I lost about $40 they said oh that's a lot less than we lost, we lost close to $50,000.....
From the emotion in their voice it was clear they were being completely honest....