In casinos definitely you will see senior persons but in online gambling you will never see elders. There you will see only youngsters because old people are fond of physical casinos and they not only gamble but also meet their friends and spend time in pleasant atmosphere. On the other hand young people always gamble online gambling from their home.
That seem to be reliable, most of my friends that are engaged with online gambling aren't too old and most of them are on their 20's. But I also some oldies but goodies who are playing online poker with an app that pays real money.
But this statistics can change anytime and there are pros and cons that will be understood by the young at hearts. These days people would love to stay at their comfort zone while doing their favorite things to do including gambling as hobby.