I think so many people are impulsive in their decision making, that digital citizenship becomes even more important. Words and actions have power to lift people up or pull them down and do damage. Unfortunately, many kids ( and adults) don't realize this until the damage has been done. It is important to teach kids very specifically the dangers and pitfalls of technology. There are so many realms that this falls into, from bullying, personal safety, as well as personal life skills such as goal setting. Technology is a great tool when used appropriately, but everyone needs to see it as a responsibility that goes along with the privilege of using it.
I agree that people (not just kids) just say whatever is on their mind and don't think about the consequences. At some point their words come back to "bite them in the rear." We have to find a way to help people learn this so they don't miss out on opportunities because of what they posted 2 years ago (which may not even be a thing they believe in).
I wonder what would happen if digital users had the right and the absolute ability to delete anything that they posted online at any time? I like thinking about different ways that the system could work and how humans would respond.