This question already has an answer here:
We can't vote our own posts in any of the SE sites. Then what is the need of showing the vote buttons to the users for their own posts?
And we display that the user can't vote for their posts everytime he/she clicks the up/downvote(mostly upvote).
We already hide the vote button for comments where also users can't vote for themselves.
If it's necessary to inform the users that message means we may show it one time and then hide the vote buttons.
It's pleasant to see the score inbetween two triangles, but it' not necessary to show those buttons after a user gets a message that they can't.(it's my point of view)