Some good points in here, like gomeravbiz, I am a male in my forties and I can see much of what you are describing. I am 20 years older than my youngest sibling, so I see this behavior all the time. I see kids living with their parents until their late twenties and early thirties too. This probably has a lot to do with socializing and finding a mate also.
More importantly, you need to understand the power of working as a team when it comes to being involved in a serious relationship. There is more to life than hanging out with boys or girls for 3 months at a time. You may find that you need someone to count on, someone to lean on, someone to help you through the really tough times that are ahead.
Most importantly, to me, life is all about making connections with people.
Don't let life pass you by!