Because in addition to funding moonshot project plays, low interest rates also fund a lot of really stupid investments that should never have been funded, and that go belly-up at the first sign of a tightening fiscal market.
When too many of those really stupid investments go belly up at once, it's called a bubble popping, and it is catastrophic to the economy.
When too many of those really stupid investments go belly up at once, it's called a bubble popping, and it is catastrophic to the economy.