It is as you said it. To be addicted to gambling comes after the need to get/ find money. This need drives people to gamble and yes, some of them become addicted. So regarding the OP's question about the reason for the rise in gambling, the answer is the bad economy that we all facing and live in. If people had their basic needs covered, then this rise wouldn't exist.
Some can still have their basis needs covered and yet still want to gamble we have people who are wealthy enough to cover up for all their basis needs but yet they still end up facing gambling addiction as a result of wanting more it start from gambling only for fun and later enters gambling to increase income after enjoying little winning from gambling which if they don’t control their self they end up getting addicted.