Self-votng used to be a default option for posts on the old chain, but I think that set a bad precedent.

If you vote for your own posts, that's one less vote you can give to someone else to support their work. It's one less chance to build the community and the relationships which boost outside voters finding you.

If you vote for yourself, you are deciding you are owed a portion of the reward pool. That sense of entitlement is selfish.