HawkMoth /Adrian's Dad- Psychoanalysis
I'm sure that many others have come to the same conclusion that HawkMoth is Adrian's dad based of context clues given throughout the series, but my thoughts in the following post will not be on proving that; rather, it will be a fan theory based off of that statement.
We know that the family has lost the mother and it has been about a year from what ever event occured. And it has shown to hit them very hard. He still very much loved her based on the painting of her and the way he gazes up at it for long periods of time (such as the movie where he starts that he needs a few more moments).
Now stay with me. He also clearly loves his son and is very protective of him. He does not want him to go to school and when confronted by his son, Adrian claims that the world isn't that bad. This may have been said because Adrian's dad had previously said this to warn him and keep him close at home. Having said that, I believe that he could have exaggerate a great fear he has, not wanting to lose his son in addition to his late wife.
This implies a lack of control, something he eagerly seeks out and tries to gain to avoid any more lose or pain.
How do people get control? Through power? Adrian's dad obtained a miraculous somehow. The old man who gave the other miraculous to Ladybug and Cat Noir once told his Kami that "he will not make the same mistake again" (regarding his selection of our two heros). What if his mistake was his selection in Adrian's dad. He chose him because he was a family man of great success who was protective of his family and cared for them deeply. But upon gaining access to this power, he saught out more. And the loss of his wife fueled the desire for control, driving him into darkness. Its almost like a Darth Vader type character, the good falling into evil.
Having said that, I don't think HawkMoth, his alter ego, is all that bad. He's terrified. He lost his wife, a beautiful woman who he cared for deeply--half his family, and now he clings to all he had left.
And those he inflicts, they were recently hurt or heartbroken. And he gives them the power to try and bring justice to themselves:. Robo-cop wanted justice. Stoneheart wanted his love. Guitar Villians musical creativity was being threatened by his labels demand for him to of conform. Dark cupid had his heart broken.
I think HawkMoth justifies himself by giving power to those who have been wronged and lets them make it right by their own means--sort of like he is going. This "secret dream" is some carnation of absolute security and preventing the tragedy from repeating itself.
I don't think HawkMoth is evil, just misunderstood.