The self-esteem thing seems to be mainly with the girls.
Self-esteem problems is much more common with boys these days, they just know how to hide it better. And some don't hide it well, if you know what to look for. Sometimes there is over compensation, and they are overly aggressive or bragging. Sometimes they withdraw into themselves and become depressed. Introverts often become depressed because they are not accepted by the extroverts and the introverts, IMO, have not learned to accept themselves as they are. Sometimes they make fun of people to feel better about themselves. And bullying still goes on. Schools talk a lot about stopping bullying but don't take action against it, especially if the parents of the bully threaten to sue.
I'm an introvert and was very shy up until I was about 40. I got over my shyness by going out of my comfort zone, and by accepting myself as I am. But I'll always be an introvert and need my "happy quiet time". I don't socialize much because others don't normally have the same interests as me to talk about. I'm an engineer so I like the details of the "why" and "how", and learning new things. But get me in a room with engineers and I'm just Mr Talky Talk!
IMO, there's also the issue that more indigo children are here now, making a path for more to come in the future. I think these indigo children have a very hard time with this earth now, their training to "be tough" and balanced is minimal so they have a very hard time here on earth. But this also have to do with their choice of parents. It's possible they chose parents that didn't push them, and so they never developed a toughness, or "emotional resilience" they need for this very difficult planet. My theory is they volunteered to help here at this time but had no idea how tough it really is on earth.