Actually there are ways to mitigate the risk...
First, this is like a 'made to order' model.
Second there are ways that Kogan can mitigate their risks...
1) Insurance. Yes, there are underwriters for everything and everything can be insured for a price.
2) Kogan can limit his overhead and exposure by reducing his expenses while waiting for the business to grow. Things like direct shipping from the factory where the product never hits Kogan's warehouse for example.
3) Initial profits fund reserves. Once Kogan can generate enough business and hold a percentage as reserves to cover loss, damage, warranty, etc ... the rest can go to pay salaries, bonus, expand business, etc ...
4) Mitigate risk... Kogan can mitigate their risks by limiting the products they sell, only to those that they have an extremely good relationship with the manufacturer and on products where there is high demand and good quality control.
While this could work, the odds are that unless you are careful, and lucky you will go belly up.
Its possible to fail simply because there are not enough consumers willing to take a risk and the economy hits a stumbling block. A consumer is willing to wait 45 days, but what about 90? That is, what happens if there's a problem at the factory? A shipping delay, etc ... Are Kogan's consumers willing to wait? Will Kogan grant a refund or allow order cancellations?
Its an interesting proposition...