why do person clone animals?

For many people, cloning raises all kinds of moral and ethical issues. As so often happens in our society, such considerations greatly lag the technology. Also, it's a lot easier to say what should be done when we're not personally involved ourselves. 

In the case of cloning, some people have such dependent relationships on their animals that the loss of the pet is extremely painful for them.  They simply can't function. Worse, when the pet has been spayed or neutered they may live with the knowledge for years that there is no way they can have another pet with those same qualities. If they believe they spayed or neutered their pet simply because someone told them to rather than this being an informed choice on their parts, the guilt and grief associated with this can be very great as their beloved pet ages. Under those circumstances, they may see cloning as a way to give their pet the "offspring" they denied the animal through breeding when alive.

Other people may believe the claims of unscrupulous companies that the clone will be an exact duplicate. To them, having such an animal is preferable to dealing with the grief they feel when the animal dies. Other people may be driven purely by the novelty of having a cloned pet.

And in all of these cases, they do it because they can, i.e. they have the money to do it.

I'm sure a whole book could be written on this subject and I'm last person to claim knowledge of what motivates people unable to deal with the loss of a loved one. However, I do know that there's an ancient Native American belief in my area that says that the primary reason is guilt. So perhaps the best way to avoid having to face such a dilemma when our animals die is to live every day the best we can when they're alive. To me, that's good advice for a lot of other reasons, too.