Asking this question reveals the lack of understanding about the topic.
If somebody invented an ASIC that is so powerful that just one machine replaces the entire current hashrate, what do you think will happen?
Will everybody except that one guy with that one ASIC just stop mining and leave OR will they try to get a few of those as well?
The limiting factor, in todays world, is energy.
This person gets it. And that energy is Electricity in particular. And electrical power works within parameters of current, voltage, and resistance, within conductors for transmission like copper or aluminum. These create physical restraints to delivering electricity to where it’s needed, further expanding the limitations of todays world for bitcoin mining.
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