Math and Energy. That's the beautiful thing. If you trust the ECDSA is secure, and you trust that SHA256 is secure - You don't need to trust the individual network participants.
If ECDSA or SHA256 were shown to be weaker than believed, they can be substituted in the bitcoin codebase (given approval of all participants, which are incentivized to ensure the computational security of the protocol).
The energy is the barrier to prevent malicious parties from rewinding history. Fundamental, understood quantities in the universe is far better than the political whims of the party in charge.
What does hyperbitcoinization look like? This infographic video provides some introduction to what this could be: https://www.youtube.com/watch?v=2pDlaOGA2ac (Bitcoin: Everything there is, divided by 21 million)