Could get ugly

i'm curious as to why?

we know he bid at an auction and three days later changed his mind. is there something we can learn from this? did he go waaaaay over is level, can't get finance, lose his job ... ?

seems a very dramatic turnaround on a rather pricey property.

with the hot market in melbourne, can he not onsell?
Since you haven't identified any personal details about the property, vendor or buyer, would you care to elaborate on the reasons? Sounds like something we may be able to learn from.
Raises a very interesting question - concerning 'interesting' neighbours.

How does one steer clear of potential 'neighbour' problems?

I'm assuming half a dozen pit bulls behind a chain fence next door would be ONE indicator.