Here is an attack that can destroy bitcoin using nothing but economics.
The Confiscation & Hack Attacks
Each Country in the world continually Confiscates Bitcoin earned by criminals and auctions it to the public.
Hired Hackers to constantly steal bitcoins from Rich People & exchanges to Sell on the Markets.
What this does is keep the price of bitcoin lower than the actual mining costs forcing more miners into bankruptcy and eventually bankrupting the ASIC manufacturers. This will eventually cause the network to enter a death spiral as the ability to find a new block will be beyond the majority of the public.
* Advantages to this attack, is the governments profit the entire time during the attacks, using the profits to fund even more attacks.
Funny thing is: This attack is occurring now and will only increase as time passes.
Even if they bankrupt the large farms with this type of thing there would always be a collective out there who could mine and keep the chain going also if the large players were to be forced out it would just hand the network back to the small miners that in turn would boost adoption further as more smaller miners jumped back on the chain. It would take some time for the DIFF to re-adjust back down but the attack would not stop miners from coming online if they thought they could get a slice of the pie again.
More people than ever are starting to understand how to store there crypto in paper wallets or hardware wallets I think over time we will see more security coming to the way we store our crypto so hackers would have a hard time hacking cold or hardware wallets.
Exchanges too are stepping up there security what we would like to see is more DEX markets that actually have some liquidity in them the reason people don't trade in them now is they have very little price action or traders there but the more regulation pushes on these places maybe in time we will see a solid DEX start that has some liquidity and can attract traders and investors to it.