Why make people afraid of such a horrible place as purgatory, when you know that it does not exist?

The Catholic Answers

I know that it does exist. And if you deny it because to you it seems a horrible place, you must deny hell also because it is far more horrible. And if you deny hell, you deny Christianity. And is it not a more horrible thought that there would be no purgatory? In that case you would have but heaven and hell. All not quite fit for heaven could not hope to escape hell. It is a much more pleasant thought that there are people not quite good enough for heaven, yet not bad enough for hell, and that these are sent to purgatory until they are purified sufficiently for heaven.

Radio Replies Volume 1 by Rev. Dr. Leslie Rumble MSC and Rev. Charles Mortimer Carty