Isnt a problem if China has 68% of the hashrate?

[exstasie]

Does the US make any components anymore?

Are we already a vassal state of China?

The whole picture changes if BTC goes to 10 trillion. That kind of money topples governments or the government topples the miners within it borders.

TSMC (Bitmain's chip supplier) is building a semiconductor plant in Arizona. They will be producing 5nm chips 4 years out from now so I'm not sure how relevant it is to BTC, but it could be a sign of things to come. https://techcrunch.com/2020/05/14/tsmc-to-build-a-12-billion-advanced-semiconductor-plant-in-arizona-with-u-s-government-support/

Supposedly miners (and ASIC manufacturers) are slowly but surely heading to North America:

Samson Mow, the Chief Strategy Officer of Blockstream, agreed, adding that “[w]e’re already seeing a large segment of Bitcoin mining move to North America.” These include Blockstream’s operations, a 300 MW joint-operation between its Quebec and Georgia facilities. Munich-based Data AG (formerly, Northern Bitcoin AG) has established its own 300MW facility in Rockdale, Texas. With 300 MW total capacity, these are some of the largest Bitcoin mining facilities in the world.

Other examples of North America’s burgeoning mining sector are not too hard to find. One firm, Upstream Data, is selling mining rigs to oil drillers to help them make better use of flare or vented gas. Another company, VBit, is establishing a 200 MW facility in Alberta, Canada.

Mow expects this wealth to run over into the ASIC’s chip manufacturing business, as well, saying “it’s inevitable” that “major ASIC companies setup manufacturing facilities in North America in the coming years.”

https://decrypt.co/27777/bitcoin-halving-could-bring-way-more-mining-back-to-north-america

[turkandjaydee]

Difficulty will decrease if people quit mining.  This will then make it more profitable for those that are still mining, or start back up.  At least until the next difficulty change ...
-snip-

Logically its "stay profitable" not "more profitable". So when there are more people who quit mining, the difficulty will still be reduced.

well based on what i have seen so far mining and how profitability and hashrate change over time is way more complicated than that. we can't really say this reason and that reason caused a rise or fall. there are many reasons involved.
of course price is the easiest to see and measure. but other reasons include the advancement of the mining equipment. for example during the 50BTC reward time people were mostly mining with their CPUs and with the mining algorithms (SHA256) that might have not been that optimized. then it was GPUs then ... and finally we are at ASICs which improve every now and then. and "improvement" means miner spends less while producing more computing power and earns more money.
another influencing factor could be fees. although most of the times it is a small factor. for instance during 2017 miners were earning up to 5BTC on top of 12.5 block reward in fees per block. that was around $30k to $40k additional income.

In my opinion, the price increase is better than other reasons that you mentioned since that other reasons also make the risk for the potential attacker becomes lower.
The chart of bitcoin network difficulty shows overall improvement and I'm sure its caused by what you said about the improvement of miners equipment that also becomes cheaper. This means the potential attacker can also have a higher hash rate easier than before.

So I can say that when this thing depends on the bitcoin price so it also depends on the potential buyers who want to buy bitcoin at the higher price indirectly. What if they don't want to buy it at a higher price?

And a high transaction fee is not good for the long term because people will hate to do a frequent transaction or at least make them think twice before making a transaction. So there will be fewer transactions.

But on the other side, this makes us realize the price of bitcoin will have a high chance to increase because it has to increase.

My point is that this has been discussed many times already. I have said my piece, it's not worth a try.

Ohhh?? I don't know the relation between your answer and the thread that you mentioned because you didn't explain it.

You talking about 2140? Again, why not look at the current circulating supply? We are closer to that 'almost all bitcoin have been mined", specially in the next 3 halvings: 2024 , 2028 , 2032. 1.5625 Bitcoin for Block ->225 Bitcoin every day. So it will be really costly to try and pull this 51% attack.

So whats your calculation about the 51% attack cost in the future?

Anyway, do you really think the purpose of this attack is only to get "more" bitcoin? And the equipment won't be able to be sold again?
If the case is as mentioned by figmentofmyass, the goal is not to profit from getting more bitcoin.

So it's clear that if it's more centralized as if more than 60% hashrate is actually gathered in 1 country, it will bring more risk to the bitcoin network.

[hatshepsut93]

that only considers bitcoin's mining incentives. the real danger of highly concentrated mining inside china's borders are incentives that are external to the bitcoin protocol.

here is one possible motive for such an attack: the chinese government forcing miners and mining pools to attack the network under threat of imprisonment.

now you might say this is an unlikely scenario, and maybe you're right, but it exemplifies the problem of thinking about this issue purely in terms of the bitcoin protocol. if the chinese government wanted to crush confidence in bitcoin this is one possible option---and since they can leverage the capital of miners (instead of their own) they can do it at virtually no cost.

It's still not fully external, attacking costs money, so even if miners are coerced to do this, they will run out of money sooner or later. The government can try to then spend their own money, but what would they achieve? The network will be down only for as long as the money are being burned, and imagine the public outcry when regular citizens will find out that their government wastes millions that could have went to healthcare or education.