using HBD equals to:

• Keeping assets 'on-chain' (HIVE), thus supporting everyone as a community.
• Keeping assets without 'smart contract risk', something which happens with all the options you proposed (they're not bad at all, but we're evaluating risk there).
• More transparency, as everyone can keep track of @seed-treasury very easily Vs a eth/bsc/matic wallet.
• No third-party risk (BUSD, USDC or USDT). HBD is Backed by the HIVE blockchain.
• The 10% APR is pretty competitive. To get that with other stablecoins you need to expose yourself to (even more!) risk.

In the end... More HBD => less HIVE floating around => more upside pressure on HIVE => more overall utilization & overall acceptance of HBD => more chances to being listed on exchanges => repeat.

Of course we're a little drop of water as a project, but every drop counts.