I think the notion that "inventory is so low" and thinking that this means there can't be a crash is really lacking. I can't quote numbers, but I'm pretty sure people were saying the exact same thing in 2005-2008. Inventory is low when demand is high. Demand is incredibly high right now because we've had decreasing interest rates for several years (just had a big drop in the spring of 2020) and everyone with assets feels rich because all asset prices are rising every day. The minute the music stops, suddenly the demand decreases. A decrease in demand means and increase in inventory.
Another thing that I think is leading to decreased inventory is the lack of foreclosures. And this isn't just due to the fact that home prices are increasing which increases equity and makes foreclosures less of a risk. This is due to mortgage forbearance and banks deciding not to foreclose for a time. I'm assuming this will end some day and we'll see somewhat of a surge in foreclosures which will help to decrease home prices.