I wouldn't buy that sign even if I was a billionaire, because I don't see any significance in it. Yeah a dude held it and it generated some hype in Bitcoin community for a week - so what? In my book that wasn't a significant moment in Bitcoin's history. The fact that it was sold for $1M is just another example that there are Bitcoin whales who sit on large amounts of coins and can easily spend $$ millions on some overpriced stuff.
I wouldn't either buy it.... But it is a thing in my book of significant happening, it made some mainstream visibility and some good meme's etc ... also just the act of doing such thing is cool imho.
Almost same thign as buying a lame NFT, i never really could wrap my head about NFTs or why they should have value but that's what it is. If an NFT could be bought for huge amounts then I dont think this buyer is crazy enough to buy this piece of paper, maybe he thinks it has value equal to what he spent on it.
What a crazy world you really can expect anything.