Compute the worth of each coalition

coalition_worth.sql

SELECT  "channels_subset",
        sum("conversion") as "conversions_sum"
FROM
    (
        SELECT  "user_id",
                string_agg(DISTINCT("channel"), ',') as "channels_subset",
                max("conversion") as "conversion"
        FROM
            (
                SELECT  "user_id",
                        "channel",
                        "conversion"
                FROM "MARKETINGATTRIBUTIONSIMULATIONS_simulated_data"
                ORDER BY
                    "user_id",
                    "channel"
            )a
        group by "user_id"
    )b
GROUP BY "channels_subset"