What’s the purpose of living so long if we’re all just gonna die one day?

There is no purpose to life.  It just is.  If you have to have a purpose or a meaning then it's up to you to invent one.

The question of the meaning of life may be asked in many ways, such as Why are we here? or Does my life have a purpose? The Bible shows that our purpose in life is to build a friendship with God. Consider some of these fundamental truths that the Bible reveals.

God is our Creator. The Bible says: “It is [God] that has made us, and not we ourselves.”​—Psalm 100:3; Revelation 4:11.

God has a purpose for everything he creates, including us.​—Isaiah 45:18.

God created us with a “spiritual need,” which includes the desire to find meaning in life. (Matthew 5:3) He wants us to satisfy that desire.​—Psalm 145:16.

We fill our spiritual need by building a friendship with God. Although the idea of being God’s friend might seem far-fetched to some, the Bible gives us this encouragement: “Draw close to God, and he will draw close to you.”​—James 4:8; 2:23.

To become God’s friend, we must live in harmony with his purpose for us. The Bible states this purpose at Ecclesiastes 12:13: “Have reverence for God, and obey his commands, because this is all that we were created for.”​—Good News Translation.

In the future, we can experience in full God’s original purpose for us when he eliminates suffering and grants everlasting life to his friends, those who worship him.​—Psalm 37:10, 11.

Becoming like God, of course.

They are the same to you.

What's the purpose of going to a party if it lasts only a few hours. 

You're such a Debbie downer. 

The purpose of living in this world is to prepare ourselves for the much better world that is yet to come.

How long is too long.

There is no purpose. People want to live longer because they fear death and the unknown. I, myself, do not wish to live a long life. 70 to 80 years should be plenty long enough for me. Just long enough to enjoy my grandchildren for a while.

“There is something infantile in the presumption that somebody else has a responsibility to give your life meaning and point… The truly adult view, by contrast, is that our life is as meaningful, as full and as wonderful as we choose to make it.”

― Richard Dawkins, The God Delkusion

Life is a test, God is real and he will give you the crown of life if you remain faithful during times of trials and tribulation