The personality of Dorian Gray is a combination of so many contradictions that we can hardly understand them. He is good and at the same time bad; beautiful and at the same time hideous; flawless and at the same time terribly repulsive. Most importantly of all: he is literally two in one - he is who he is, a living existence and at the same time a portrait, a visible reflection of his soul.
The issue is that Dorian is not the only one who has a distorted view of true beauty. He knows well that most people tend to confuse external appearance with inner beauty and for this reason, as much as he can project an image of a sinner outwardly, he can freely sin. It is true that terrible rumors surround his name, but the people who know him up close cannot believe them. What keeps him going is his perfect "image" - he lives exclusively for physical pleasures and derives pleasure from his own aesthetic advantages.
Dorian stubbornly finds pleasure in his useless and corrupted soul. He is not concerned about his portrait because he feels guilt, but because he fears that his secret will be revealed. And the most terrifying secret of all is that the problem is not the portrait itself, but what it means to Dorian, the way he sees the portrait. He is fully aware of how wicked he is, but he does not want to do anything to change. He is fascinated by his wickedness, he loves wickedness. At the end of the novel, it is already too late - despite the apparent innocence and incredible beauty, the real Dorian is irreversibly evil.