I also don't know for sure what causes some members of this forum to write spam posts. However, for beginners it is still normal if the writing is still spam, because they are still in the learning stage. But for members whose ranks are already high, I also don't understand why there are still people who write spam. In fact, if you look at the ranking status, it is clear that this member has received many rewards from his posts which are definitely of high quality. But why do you sometimes still make spam posts?

The answer may be because there is a posting target that must be pursued.
Or because are busy.
Or the member could also force a post on a thread he doesn't understand.

Because of the three factors above, in my opinion the quality of posts can decrease and they can end up being spam posts.