How did you solve this issue in your version of unprofitable PoW?
I discarded proof-of-work and formulated a consensus ordering design concept different than just proof-of-stake, DPoS, or a DAG.
Yes, I see. You discarded your original plan of using unprofitable PoW, but this is not exactly what I asked. I imply that you don't want to tell us more about your discarded unprofitable PoW scheme, even though it might offer further insights why current systems (that you are critizising so vehemently) are flawed.
I am doing my best to share why I abandoned unprofitable PoW within the limited time I have to share.
I am not going to share the scheme because a facet of the scheme is employed in my ongoing (current) solution, even though my current design no longer employs unprofitable PoW. I am instead burning transaction fees and using TaPoS to prevent long-con nothing-at-stake attacks. But the "longest chain rule" is not the
default consensus mechanism in my design. I can't give more details than that right now. My design has multiple facets which are (afaik) novel.
Other than
rented hashrate double-spend attacks for the PoW coins that don't use ASICs, as I point out in detail in my white paper, the main concern is the 51% attack is not for issuing double-spends (which I agree they won't do) but the majority hashrate can have a monopoly on all the mining rewards in the system by orphaning the other blocks in the system (and in a decentralized minority case, this attack isn't even detectable!). That is an attack and it is insidious (harmless) enough that users of transactions probably won't care, especially given the "benefit" that 1 confirmation becomes a guarantee and can't be orphaned (because the network becomes controlled by a deterministic mining cartel).
This is an interesting attack vector but I don't see how it is applicable to
unprofitable PoW schemes like the second one I suggested. If the mining reward is limited to preventing a loss of stake or decreasing the tx fees (which cannot go below 0 %), there's no incentive for 51% miners to orphane other blocks. Such a behaviour would inevitably deter honest stakeholders/miners from using the currency, so that the coin would eventually depreciate and hurt the attacker.
Also, in case of negative interest rates applied to the stake, the power law distribution is counteracted by the fact that small stakeholders could use the idle power of their devices while large stakeholder would need to buy or rent extra hashpower to preserve their stake.
I explained to you that your negative interest idea could be attacked by a 51% attack which enables
only the majority to retain stake by orphaning the minority's blocks. So it is just an obfuscated minted block reward. That is not
unprofitable PoW.
Additionally I explained to you that if you did indeed have
unprofitable PoW then it would have insufficient hashrate and it could be attacked very cheaply by renting hashrate.