An old boss of mine was a whale. He was in his 40s and spent 100s of dollars on mobile games. I think it's mainly people with a lack of impulse control.
Spending hundreds of dollars on mobile games doesn't make someone a whale imo. More like thousands or tens of thousands over years.
Someone I worked with had a nephew who spent $4000 on I think it was FarmVille in one month. It took them a while but they were able to recover the money because the kid was underage and using the parents credit card.
I left out the word "regularly". I'm sure he would have spent a thousand every few months, at least.