Agree with you but unfortunately there are vibes that this will be the trademark DPC drama that may or may not make complete sense (ie recent Quinn) and you have no control over in episode VI or VII. The game opens with the MC saying he and his dad didn't have much, but he was happy back then (pre letter in this case) and that they had each other. Some of his conversation with Jill, in her bed and especially in the new episode about how bad being cold is when you have no money, give some concern that he will be upset finding out he always should have had money and thus good insulation, working heater/water, etc. The MC may then take it very poorly and have issues with his father. Even more daddy issues than he already has going on with Tommy.
That opening monologue might be more telling that it seemed at first read. I always looked at it as being about the DIKs and other people he would meet at college and how they will become his new family, but there are parts that could also refer to the possible
lineage of his Mom.
"Family. My Dad once told me family was more than
blood relations.
Being related doesn't necessarily make you family. Family are the people who support you in your choices. Family will help you grow.
Family doesn't give up on you in times of need. Family are the ones who love you for you, whoever that may be. Even if
you lose your family, or
your family loses you. Don't stop. Find new ones to love and somwehere else to call home."
Since this is a retrospective monologue, it's possible these lines refer to the reveal about his Mom that we will get later and his dealings with the rich family that his Mom came from. Then there are those other lines later on that you pointed out:
"Either way, I was happy back then. We didn't have much, we...erm...we had enough."
Sounds like he's remembering a simpler time before he knew the truth and maybe even points to an issue with his Dad withholding the truth since he hesitates when talking about him, almost as if he was about to say what their relationship was like back then compared what it's like when he's giving this monologue.