The purpose he's  making it more solid to uphold investors beliefs ,
For instance you have a software with users  and you sold the name  of that software written on a piece of paper  for a huge sum , you should expect more users of that software without stressing it,
The part of beign a good investment  in term of FIAT compared to other writings like Einstein is hard to determine because  I could relate something like this to that of a NFT ( some NFT bought with hundreds of thousands are now worthless now) just saying the opposite might be achived amd he mightsold it higher,probably  he's  just buying to add to his collection .... hang on a wall just as you've  said maybe forever.
The Seller bacame recognised   after he brought 3.7% increase in the price of Bitcoin besides he has being  digging for some time now 

In 2019, Langalis created and sold 21 replicas of the sign, which sold for an average price of 0.8 BTC, worth about $51,300 today.
Source
This is soft...