If you need to hire 1 more developer at $100k to help maintain your data warehouse or pay $100k for Snowflake or BQ, its a no-brainer to use SaaS.

Also humans cost more than their salary: Recruiting, management, benefits, attrition, vacation, the risk that they are just not capable.

A human will also cost you more year over year (raises, promotions, etc), SaaS will typically cost you less year over year (optimizations, negotiations, competition, etc).