I'm afraid that self-custody isn't even the solution as self-custody currently requires to control at least one UTXO and growing the UTXO set to 8 billion would be unfeasible in a short time frame.

I think we need some "Uncle Jim" approach, where it is easy for some to provide custody for others in a much more distributed way than 3 big wallets holding all the funds.

The best solution I could think of right now are chaumian mints with both the UTXO set and the minting requiring m-of-n signatures, combined with tools that allow users to join or form federations dynamically.

Until that is ready, joining your Uncle Jim's Single Sig BtcPayServer is better than using WoS for sure.