Someone may start gambling for fun
I don't really believe in this.
Most gamblers do start gambling it is either they have encounter or seen someone earn a lot in just a short period of time. That is when they will feel of starting gambling having high hopes of also winning a lot. It is not actually to have fun, it is just an excuse of people due to losing most of the time.
Which is the main reason for your gambling activity?
The main reason is for financial, I want to win money just like most gamblers. There is no reason to use gambling for fun or just to have the feeling of thrill or what. Gamblers do not spend money just to lose, we always hope for the jackpot.