It wasn't at first.
Life lost all meaning when I hit adulthood. I'd compare it to realizing that there is no Santa or Easter Bunny. Adult life was eating, sleeping, doing uninteresting drone work, and paying the bills and taxes. Over and over, until you die. I had no religion to comfort me with the offer of a happy place after death. The idea of sharing the misery with someone, and bringing a child into it was horrifying.
I saw America as a consumer driven society. We're not people, not citizens; we are consumers. If we don't spend our money like idiots, the economy will collapse. But moving to another country would only prove that the grass is not greener anywhere else, there is no paradise to be found on the earth. Yet, I didn't want to live in a fantasy world like some lunatic bound for the insane asylum, or drink and drug myself numb. Upon becoming a real adult, I finally knew the ugly truth. There was no Santa.
So what's different now, what changed? What repainted the picture of life I described above into something interesting, and even fun?
*As I sit here writing this, I wonder if I should tell the answer. There was a lot of fun in discovering it for myself*
I should say a few things, but I think giving it away would be a bad choice. I don't want to sound like I'm quoting some worthless self-help book either.
I'll just answer your question. Yes, being an adult is fun. Life just keeps getting more and more interesting.
Like adults tend to do, I'll leave you with some advice. Take it for what it's worth. (it's free

)
Don't pursue things for the sake of security and life will be more fun. Security is like a mirage in the desert.
Time is definately not money. Remember that.
Oh yeah, there really is a Santa. How do you think your presents got under the tree?