>Why would the supply of money/loans increase unless people were taking out loans to buy houses more than usual
Because the regulations that limited supply of loans disappeared.
Consider that many more people want a million dollar home than can qualify for the loan (afford it).
Think about how much a single change in regulation would effect the number of people who can qualify for the loan/afford the $1M, example: cash down payment. How many more people can afford a $1M if the regulations for the loan approval require cash down of: 100%, 20% or -3% where the bank pays you $30,000 cash to take the $1M loan to buy the house.
Allowing people to finance 103% of a $1M home significantly changes the number of people who can act on the want (demand), to the extent supply of the homes drops and as a result their prices artificially increase supported by more bad loans.