Kingdom of Cards - Meaning

Hey there, thanks for taking the time. I'm listening to this song quite frequently and I'm puzzled most of the times. Maybe someone here can clarify on this part:

I thought I wanted legacy, I thought I wanted fame
I didn't know I'd lose all my loved ones in exchange
Left 'em all behind and yeah, for that, I am ashamed
But that's the price I'm paying 'til I'm buried in my grave

Gave it all to burn forever underneath the rain
Drowning in the present of a past that I couldn't change
Writing songs instead of letters because I'm too afraid
Afraid of coming back to find that everything is the same

l do it all over again from the start
And this time, you're not leaving me in the dark
You took me for granted, now look where you are
Atop of a kingdom you built out of cards

So in the first verse, the person clearly shows regret and states, that he's ashamed for leaving his loved ones behind. He gave it all, despite overwhelming odds, and still suffers from his past. And now follows the part that confuses me.

"I do it all over again from the start

And this time you're not leaving me in the dark".

Why would he do it again if he is ashamed and regrets? And what about being left in the dark?

If there is on open thread on this somewhere, I apologize. I really didn't find anything. Some explanation I did find in "Genius" though that part was missing. Thanks to anyone who gives their opinion :)