Can't speak for all kids, just mine who was certified at 12 (now 18) and has had the opportunity to go on many 3 week dive vacations. He informed me he does not want to dive anymore. Reason given is resorts and boats have had virtually no kids his age to hang out with. He did enjoy rescuing bikini clad models for rescue class. Many dive resorts are sleep/eat/dive variety with not a whole lot of other billed activities for younger kids who aren't worn out diving. He has experienced first hand rude divers who have "assumed" due to his age he did not possess the skills to be on advanced boats despite never having observed him diving or experience. They also assumed he didn't know how to shoot a DSLR. He was taught better than to say shut the ----- up and dive already. Respect....it works both ways. I just told him to ignore the idiots, be first to jump, exhale and let it go. When he was last back on board with great photos, the divehards finally grunted approval. He just got tired out having to defend himself when we went somewhere new. There were only a handful of strangers that came up and said anything encouraging. It really means a lot to a younger diver if they are acknowledged, made to feel like they are welcomed and not an intrusion into the geezer club. I'm not talking about boat crew who are paid to be hospitable to customers but other divers on boat. They just want to be accepted, not pampered, and certainly no hand holding when it comes to gear set-up etc. Don't assume, observe, then comment.
So, basically every diver out there can do something to encourage the younger divers! Speak to them.
And, the newer divers who might have the heebie jeebies just a wee bit. Sometimes sharing that we all had the heebie jeebies at one point or another starting out helps them feel better. Just encourage them to take their time, not rush, don't go beyond their comfort level means a lot, especially their first few dives with no instructor within arms reach. We are all out there to have a great dive and be safe doing it.