Time accrues.  What you do when you are young is more important not just because those are your formative years but because those memories will live with you as long as you are alive.  The earlier the memory the longer it lives with you (and influences subsequent memories).  There is also the fact that you may need the people you knew when you were young when you are a lot older.  There are lots of times in life as you get older where people are just not open for relationships.  When you get in a situation where this is true you look back and wish you would have done better with the relationships you had in the past.