It's not a spurious amount or, if it is, it's only because you won't give the exact amounts but are insisting on a claim so ridiculous the only way anyone would believe it is if you could provide figures to back it up.
The amounts are only based on what you've said. First of all YOU said they'd spent more than 2xaverage uk house price in rent. So 2 x £285k = more than £570k.
Then when I said those figures made no sense YOU said "I suspect that they probably spent more than that on rent" and YOU also said "Just scale it up or down as needed if that helps you relate"
So I tried scaling it up and the numbers still didn't make any sense.
Tried scaling it down and they made even less sense.
It's not the 50% reduction that I'm obsessed with, or that's the issue, it's your insane claim that they have now bought a house in 2023 at the same price it would have cost in 2008! I can't see any evidence of house prices dropping anywhere near that much anywhere in the country.
Now you're saying that prices have dropped that much commercially. So, irrelevant to the RESIDENTIAL property your colleague purchased?
And that they managed to afford this drastically reduced home because the cost of the house was 3 times the savings they made in rent.
Thus by your own information they spent somewhere between £570k and £1million in rent over 11 years. Whilst also managing to save for a deposit for a house costing between £1,710,000 and £3million, which magically is the same as it was worth in 2008.
If you a) can't suggest figures that make any sort of sense with your claim and b) think those figures are anywhere near relatable or achievable for the majority of the population, then don't be surprised that people don't fall over themselves to agree with the point you're trying to make, because it's very obvious it's all completely made up!