> Even without proof of stake, it's possible to make transactions low-cost. only at the cost of reversibility. the central thesis of proof of work is that an

> Even without proof of stake, it's possible to make transactions low-cost. only at the cost of reversibility. the central thesis of proof of work is that an attacker must expend more energy than the "main" chain, across the duration of time they want to be able to reverse a transaction (older transactions require more time). The amount of energy expended is determined by mining rewards - over time, mining profit will converge to zero, miners will expend however much energy the mining rewards buy. as such - any reduction in energy expenditure (i.e. a reduction in mining rewards) will lead to a reduction in security, making it easier to reverse transactions.