so you know they were selling at >50% profit margin few years ago...I'm sure no one would cut a loss-making deal..so the cost of the house when they first bought must be <600k.

Typically developers take 30% profit in any development. When they sell you at discounted price, they still probably taking 20-25% profit.

The 0% down is a similar concept with those guaranteed x% rental return scheme. It is a zero sum game. Sure they have factored in the 'discounts', which means inflate the selling price and market it as discounted price.

Why need to blame? It is a great news for most people who wants to buy a house, if property market declines means house prices are going down.

I think you are mixing up between flippers vs home buyers. Home buyers do not "go to market" (that is for trading) but buy for own stay, so they care less about the value of the house for short term since they are not selling it right away for profit, so if it is a bargain they will snap up (I would).
Flippers, on the other hand wanted to maximise profit, hence they will not enter the market when sentiment is low, because chances are they will be unable to sell anytime soon, unless they have the holding power.

Housing 'bubble' is different to the 'bubble' in stock market. A failed company can dies off if the fundamental is bad, no matter how long the time you give it. But real estate, on the other hand, will definitely grow. There's a saying "buy more land, they are not making it anymore". Especially in Malaysia where the population is still on the growth. Housing demand will be there, in time.

When prices drop 20 or 30%, the flipper's bubble bursts because they profit less from selling (if they sell) to own-stay buyers, who may get a discount. It is not a bubble to own-stays. But if those flippers has the holding power, yeah, it will still be a good investment, only it takes longer (years) to see returns. It is fine, because usually the prices will go up by more than 100% before dropping a mere 30%, there is still increase.

Remember, bubble don't apply to most of the population with housing needs, they apply to the riches speculating the market. Somehow the media has projected the image as if a bubble bursting will affect the entire population in a bad way.