For sure the scalability, reliability and maintainability of the EOS network (infrastructure) will cost a lot. So, what are the main benefits of being an EOS Block Producer?
Block producers will be rewarded with EOS tokens.
A blockchain using EOS.IO software also awards block producers tokens every time they produce a block.
A blockchain that adopts the EOS.IO software will award new tokens to a block producer every time a block is produced. In these circumstances, the number of tokens created is determined by the median of the desired pay published by all block producers. The EOS.IO software may be configured to enforce a cap on producer awards such that the total annual increase in token supply does not exceed 5%.