There are arguably legitimate reasons to mark own responses to own questions as correct or helpful, but not when other people have responded with useful or correct answers.
I think the following are not legitimate reasons:
- Being embarrassed to leave an impression to have been unable to fix an easy problem.
- Ego or demonstrating cleverness to have fixed the problem without the help of others.
- The OP indeed found a solution meanwhile, but did not inform others.
- Annoying others who provide useful responses.
- Attempting to get points to elevate the own user profile.
Sometimes I would like to tell people to remind me not to bother responding to their questions and not to waste anyone's time, but that's hardly the best way to pursue.
There are already a few ideas to address the issue. However, instead of a message pop-up or simply not allowing people to mark their own responses, I suggest adding an explicit note to the forum etiquette, outlining that people ought to evaluate the responses they received in order to mark correct and helpful answers. People should not mark their own posts as correct or helpful when responses by others exist that contain information leading to the solution. It is a disrespectful and rude behavior.
It is easy to spot in many cases, but difficult to criticize when being the victim yourself, because it could be misinterpreted as an attempt to obtain points in an unsolicited manner, which is prohibited by the forum etiquette. I think an appropriate entry in the forum etiquette would help people on the grounds of marking such postings as "abuse" for not complying to the forum etiquette. I think this is a better approach than leaving people to self-police the issue.
Previous discussions and ideas regarding the subject: