Building and maintaining a custom reverse ETL (reversing the flow of data from downstream operational tools back into your data warehouse) solution can be costly, both in terms of labor and resources. Assuming an average annual salary of $200k for a data engineer, the initial cost to build a bespoke reverse ETL tool for three CRM connectors could range from $24k to $8k per engineer per connector, with ongoing maintenance costs that can balloon beyond initial estimates. In contrast, using a pre-built reverse ETL tool like Census can provide significant cost savings, including unlimited connectors and destination fields, scalability, and API quota management. Moreover, investing in a reverse ETL tool can free up talent to focus on higher-value work, such as unlocking business value through models and applications, rather than being bogged down by maintenance tasks. Finally, building a custom reverse ETL solution is a complex endeavor that requires specialized expertise and consideration of factors like data governance, write APIs, and organizational use cases.