Extending this further, based on the stated value it looks like he probably had 40 or 50 ethereum. He might have bought them for a fraction of today's price - say $50 - so might only be out $2500 based on cost at transaction time...

If someone made away with all my retirement savings, I wouldn't say I was only out the cost basis.

That was pretty much my point!

Yeah, I missed that.

Your analogy is different. They bought for X, then when it was stolen it was worth 80k, and at this random time today, it's worth $120k and he's saying he lost $120k.

Value is arbitrary, and only crystallises at liquidation. I have a painting I paid £300 for. Works by that artist are now selling for £10000. Does that make my painting worth £10000? I can send it to be appraised but even if it is valued at £10000 that value could only ever be realised if I send it to auction. If I wait too long the artist may fall out of fashion and the work may be worth less than I paid. The real value is the pleasure it gives me each day when I look at it. Is that worth more or less than £10000?

Be that as it may, it's missing the illogical point the other person raised. If your $300 painting was worth $10k when it got stolen from you, but 7 years later the market value is $1M, you don't say "I was robbed of a million"

I have a feeling if ETH went down in the meantime, blog post would reflect 80k, not the lower value.

Incorrect. Author may not have had the required savings to rebuy the position he wanted.

The author can simply buy a "position" in Monopoly Money instead. It's just as useful as cryptocurrency, and as a bonus harder to steal!

But harder to resell for a multiple of the buying price later.