No, it doesn't. In rare case, you may lose few of your activities. Otherwise, there's nothing wrong deleting your own post. Why though? I don't think there are a lot of reasons for deleting your own post.
There should be other reasons why people delete their posts, but I just gave the ones I have experienced.
Most persons delete their post because after posting they read through the post and noticed they were going off topic, so the feel its best deleting the post than letting the mod do it. In my opinion if a mod deleted a post then you should take it as a criteria to always to always read through your post and think before posting them on the forum. A lot of persons dont go through their post over and over before they post and this has cause them to loose one way or the other.
Also most post that are deleted by mod or the owner is as a result of the post being posted on the wrong board. This kind of mistake are mostly done by beginners and those who are still learning in the forum and most times they dont know where to share their thought so they just post it anywhere. Lastly some post are deleted because the image shared in the post is not conveying the message the user is trying to share in the opened post.