If you have never been in a nasty, slimy pit, you may have a hard time relating to someone who worships God for getting him out of one. You might think they are exaggerating a bit or just asking for attention. 
It is important for those of us who were fortunate and prevented by grace from growing up in a godless home to respect and appreciate the deep gratitude of others. Were it not for the Lord’s kindness, we, too, would be wearing those scars or fighting ugly memories of the past.
The Psalmist’s song is an invitation to praise the Lord for the amazing grace that protected us from or brought us out of the hideous hole of sin.