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"