Why wouldn’t yimbyism just collapse the economy?

I often see economists proposing that we build more houses to lower rents and house prices. Now, I have always wanted lower rents and house prices as I am of the generation that is priced out of home ownership where I'm from in the UK.

But thinking it through, as I have been learning more about economics, wouldn't lower rents and house prices result in a large number of households going into negative equity, maybe even triggering deflation as people stop spending, maybe even resulting in many buy-to-let landlords and other businesses defaulting on their mortgages and other loans and thereby creating a banking crisis?

Is it expected that building the houses will take long enough that it won't be a sudden shock or am I just going wrong somewhere in my reasoning?