On the second - it sounds like you're reversing course on your original comment about how deregulation was the root cause of the poor taking on inappropriately large mortgages. Or do you maintain that view?
Deregulation made it possible. Heck, if I remember right that "the poor could get a credit for the house that they cannot get under the old rules" was even an explicit reason.
So yes, you could say that within all the factors, it was the root cause, because the existing rules prevented that.
As a government, your job is to do what is best for your people.
Sorry to correct you again here, but this is a
really really important point that has to be understood if you talk about politics at all.
What you described is how you want it to be. The reality is that as a government your job is to follow the orders of the leader.
And the leaders main concern - above all and everything - is to keep the power.
You do this by paying favors to the people you need to do this. In dictatorships that is the military. That is why the military is well paid (especially the generals, often indirectly) and big even (or especially) if the country is poor.
In a democracy with the troublesome election system, the number is too big for private (personal) rewards, so you have to pay the favors through policies. One well known example are farming subsidies. It is used everywhere because your other essentials are seldom going up in arms to protest that, they may even like it.
That money thing is also why Republicans hate giving to poor colored people - because they seldom vote Republican. It would be giving money to the enemies! At the same time giving that money to your group is good, of course. That is why white old men think social security is a great thing.
And the important point here to remember is that even if you are the most civil minded president ever, you can only use money that you have
after paying off your winning coalition to do your projects.
Because if you don't someone else will take your place by promising more rewards.
That is also the root why so many election promises are not realized. Even if the leader wanted to, he can't.