If 10k users are using the dashboard at the same time you end up to 10k queries to the Snowflake DB.
Not sure Snowflake will handle it and if its an cost issue.
Your DB is updated real time?
To be honest, I have used 90% SPICE datasets so far. Because the performance is usually better and no real time data is required. A daily refresh of the SPICE is usually cheaper in terms of costs and resources than DirectQuery.