What Is the Primary Incentive for a Bitcoin Miner to Include Transactions in a Block?

The primary incentive is the total reward for successfully mining a block, which consists of two parts: the block subsidy and the aggregate transaction fees. The block subsidy is a fixed amount of new cryptocurrency created with each block, which decreases over time through halving events.

Transaction fees are paid by users to incentivize miners to include their transactions. As the subsidy diminishes, transaction fees are projected to become the sole or major source of revenue, ensuring network security.