e.g. some EVM chains have a majority of "stake" in either one country or several adjacent countries (particularly in Asia). A cable cut there, which the article points out has happened, can lead to the blockchain getting cut off or even halting.
It might be difficult for you or I to profit from double spend, but remember, the threat profile is entire countries, and if any of the heavy-hitters wanted to kill BTC the logistics of conducting a big gnarly double-spend would barely register on their existing cyber budgets.
Back in the day, these scenarios were fanciful because crypto was small-league and the viable threats were big-league. Since then, crypto made it to the big leagues, but I don't think it ever became capable of handling big-league threats. At some point it will have to reckon with that.
I'm not sure you really understand what a double spend is. It's not actually a big deal in the real world. An attacker capable of double spending is simply capable of reversing blocks, therefore reversing transactions.
So, for example, an attacker could buy a house with BTC, and then when the papers are signed, reverse the transaction to get their BTC back. But in the real world, the victim would just go to the police and get their house back.
The only plausible "big league" threat would be a government investing billions in ASICs to perform a 51% attack and grind the network to a halt. But the Bitcoin community would probably quickly move to a new Proof of Work algorithm and render their ASICs worthless.
We saw a similar thing with supply chains and chip suppliers.
Then also remember that the internet haven't seen a global outage since forever, worst parts have been when some submarine cables break and traffic has to route around it, but never has the entire thing fully went down. Considering how most of it is built with bandaids, silver-tape and WD40, it's surprising it is as resilient as it is.