A Sybil attack may happen when one physical user has 51% of the users of the onzecurrencey blockchain in possession. This is in fact a new alternative to existing blockchains and consensus algorithms like proof of work or proof of stake, and this consensus algorithm is named poco or proof of chosen ones. Please read the whitepaper for deeper understanding of poco at <https://github.com/nvrrdt/onzecurrency/raw/main/papers/whitepaper%20onzecurrency%20crowd.pdf>.You'll find the reference implementation at <https://github.com/nvrrdt/onzecurrency>, which is work in progress.
The advantages of this blockchain are a modest energy consumption compared to proof of work, a fairer distribution of rewards (wip) for all its users compared to proof of stake and regulation could be done more easily for entities who control identities through a unique physical recognition.