There are responsible and irresponsible shooters. Some are old, some are young.
That said, some age groups have a little bit of a head start on responsible, safe gun handling while some age groups probably start out with a bit of a disadvantage.
One of my young relatives has spent literally years playing with airsoft airguns. As a result (although it's not a given that everyone who plays with airsoft will be this way) he has absolutely zero sense of muzzle control or trigger finger discipline. An unintentional discharge, in his mind, has zero consequences and he's never been interested in learning otherwise. I tried to work with him a little bit and had to give up. His years of treating gun-like objects like toys and his attitude made it dangerous for him to handle firearms and I was unable to change his attitude or his behavior.
Is that an age-related issue? Not directly, but airsoft is a relatively new phenomenon and it's less likely that someone well into their middle age has extensive experience with it.
To some extent, some video games also teach habits that can be counter-productive for someone trying to ingrain safe gun-handling skills, and again, it's a little more likely that a person with extensive video game experience is going to be on the younger end of the spectrum.
Does that mean that people who use airsoft or play video games can't handle guns safely? Not at all. But a lot of experience that effectively trains the body and mind that a gunlike object can be handled without care can be difficult to overcome.