Why do people care about the afterlife?

Because retirement at the country club sucks,

and I want a brand new body without wrinkles and arthritis.

Most of the people who believe in an afterlife believe that actions and behavior we exhibit in this life have a huge effect on our condition/happiness in the afterlife.

I mean: it's a little like asking:

Why do people care about the after high school? You cant control it, you cant know what will happen, and the debate over it divides humanity... Why do people care about it, we all eventually leave high school and we all have problems do we really need to have stupid arguments over things nobody has an answer to (like, "Is getting good grades important? Or should I concentrate on learning a trade instead?")

Some of the decisions you make in high school are believed to affect your success, your happiness, after high school, even though things beyond your control might cause such decisions to have little effect...

and the same is true of people who believe in an afterlife. They believe that decisions you make in this life will affect your "success" in the afterlife, even though it is not certain that specific decisions will definitely have the expected results.

Because they never bothered to learn the religion they claim to follow. The bible calls itself the word of life. Jesus said he came so people could have life and have it more abundantly. Churches don't teach doctrines, preachers don't preach doctrines, and people don't go looking for doctrines, so they only know about the baloney they keep hearing from random people. And that baloney is preoccupied with death and after death. "Afterlife" is only a source of jokes.

Read a chapter of Proverbs every day. Proverbs has 31 chapters so you can keep your place by just looking at a calendar. There is no religion or nothing in Proverbs and you don't have to believe anything. Just read every day. When you are comfortable with that, then read the bible from Romans to 2 Thessalonians over and over until you start to remember what it says. That is the part that applies to Christians.

It is human nature, we all have an innate fear of death. It is the fear of death being a final ending to a life, and humans only wish is for some form of immortality. So, this fear makes them strive for a place that will allow for another plane of existence, to experience that immortality beyond this life. That is all, nothing more. Heck, I know there is no heaven or hell, I know once my lights go out that is it. I will be placed into the ground and my body will be nothing more than worm food and fertilizer to the soil. Kind of s u c k s, but hey what can you do. Nothing really, except in the case of religion and that is to create your own little happy place to make your life a little bit easier to accept.

Why waste the one life you get in the vain hope of getting another to waste? - David G Manley

Be thankful that you have a life, and forsake your vain and presumptuous desire for a second one. - Richard Dawkins

We can decide our fate by believing and doing righteous deeds. Allah answers us thoroughly about what will happen in the afterlife in our Holy Quran.

Being a part of creation and yet not knowing creation, that is our fate.

We have no control upon our thinking too.

God has the answers, and has revealed them to us in the Bible.

Because it exists. You will be there and you will be either with God or with Satan forevermore.