the speaker has probably gone a circuitous route in determining that the purpose of life is life itself. It's natural to speculate the reason behind the existence of life, but I agree that it's more advantageous to use that time to fully experience life. You'll go in mental circles wondering about the reason behind life, but all you can know for sure is that you have at least this life to live, and the best thing to do is to enjoy it and make the most of it.