I'll add one more data point to the thread;

The timing and pricing of investor selling is different to residents selling.

Residents sell (mostly) for reasons other than profit. They might be moving up, or moving away, or whatever. There's some pressure to "get it done" so they can move on. They can't really afford to "time" the market.

For investors there's much more "buy in the down, sell in the up". Except that it's been going up for a while, so there's no motivation to sell at all. It would be uncommon for them to accept a loss. Even unoccupied it's (mostly) better to hold rather than sell at a loss.

As mentioned elsewhere, overall market penetration by investors differs wildly by market, and segment. So 3% overall might sound low, but 20% of a dwelling type in a specific market is plenty to alter market forces.

I say this as someone who has owned property as an individual, and also worked in a business that invested in property.