The current incentive to lock YFI tokens is limited, as there is not much voting taking place at the moment. However, this could change in the next two weeks, as the YFI governance system is still relatively new and is still being tested. As the system matures, more voting opportunities could become available, which could provide more incentives for locking YFI tokens. Additionally, locking YFI tokens can provide holders with a higher yield than simply holding the tokens, as locked tokens can generate rewards from staking, providing liquidity, and other activities. As the YFI governance system continues to grow and evolve, more incentives may become available for locking YFI tokens.