The legacy players like Teradata and Exadata (from Oracle) really don't scale. Teradata has ~2B in revenue, Exadata is probably in the same range. That's all up for grabs but that's only scratching the surface.
Historically, only transactional data was dumped into the warehouse. Snowflake is selling storage at S3 price (plus you get compression so often ends up cheaper) while they are making money of compute/query. If they can provide all the right query abstractions (SQL, full-text search), in theory all data can be thrown in Snowflake. Yes, tech savy bay area companies can setup their own stack using Presto etc but rest of the world is not like that.