The thing is OP, if there was to be a crash it would only affect those who are in a very vulnerable position. It doesn't affect those of us who have big 'forever' houses since we simply stay put and ride out the cycle. Those with spare cash might swoop in and buy up cheaper property to rent out.
Similarly those people who just fancy moving house just decide not to do so. They stay put and wait (or if they are upsizing they might decide that a 20% hit on the price if their house is well worth it since they'll save more than that with the 20% reduction on the house they're buying).
Investors on the whole have lots of cash. They have bought as a long term investment. They're not going to dump their properties when the market drops, that would be a very strange investment decision. They will hang on and ride it out.
For those in small properties with growing families who really need to move but don't have a lot of equity in their homes because they bought at the top of the market and could only just afford to move anyway it might no longer be possible since they might be in negative equity. So they stay put too but struggle with space.
The people who really suffer if there is a drop are:
Those who could only just afford to keep a roof over their heads anyway and can no longer afford their monthly repayments. These are the people who lose their jobs or become ill and can't work, can't afford their mortgages and end up with their house repossessed - good luck swooping in on those
Ironically they are often those like you who have struggled to get onto the property ladder in the first place.
Those whose families are breaking up and they are forced to sell due to divorce etc - good luck with those too

Those who are elderly and need to go into care and are being forced to sell their homes to pay for care or who can't cope with their properties and are struggling to manage

etc.
But it's ok for you because you finally manage to buy your London flat from one of these groups of people (assuming of course that your job is secure and you can still afford a mortgage with the inevitable interest rate increases).
Do you see how people might get annoyed with you for wishing down the market and trying to worry people? 