Why does Trump constantly praise himself despite the fact he's a petulant loser who's accomplished nothing on his own?
Because he's mentally ill.
He takes credit for other people's accomplishments and blames all failures on other people, so always praises himself. Mr Big Head became President Big Head.
He lies and Christians love him for that. To say that President Donald Trump has a casual relationship with the truth would be a gross understatement. He has repeatedly cited debunked conspiracy theories, pushed voter fraud myths, lies about immigrants and crime, and embellished his record and accomplishments.
I Eat Pizza 1996
He has ASPD
Kinda reminds you of King Barry the Great, THE Legend in His Own Mind, doesn't it, honey. <sigh>
He is narcissistic