The main benefit of buying the old BTT token (TRC10) is that it can still be used for the token migration process. When the project transitioned to the new BTTC token (TRC20), it introduced a migration program allowing holders of the old BTT to swap their tokens for the new BTTC tokens at a specified ratio. If the old BTT tokens are available at a lower price than the current BTTC token, this could present an arbitrage opportunity to acquire the new tokens at a discount after migration.
Additionally, some exchanges and wallets might still support the migration, so it’s important to check where you can convert the old tokens. However, keep in mind that the main focus of the ecosystem is now on the new BTTC token, so using the old BTT primarily for migration would be the most relevant benefit.