30% was a great deal when KDP launched..several decades ago..Prior to KDP, self-published authors would have costs of about 90% to print and distribute their own books. Traditional publishers generally take 85% but in exchange handle the editing, marketing, and physical logistics of book printing and distribution.
Similarly, when Steam launched, its biggest competitor was retail. Studios got paid a % of the wholesale price (after the publisher recovered its costs), which worked out to an average of approximately 10-15% of the retail price for successful games and 0% for unsuccessful games. (Note: this does not include the milestone payments to the studio during the development of the game.)
But markets have changed. 30% may or may not be a great deal anymore. (For KDP, many authors say that the 30% is worth it because the volume of their Amazon sales dwarfs all other-channel sales combined. Some relatively famous sci-fi authors have said that about 90% of the sales of their self-published works were through Amazon.)
Similarly, when Steam launched, its biggest competitor was retail. Studios got paid a % of the wholesale price (after the publisher recovered its costs), which worked out to an average of approximately 10-15% of the retail price for successful games and 0% for unsuccessful games. (Note: this does not include the milestone payments to the studio during the development of the game.)
But markets have changed. 30% may or may not be a great deal anymore. (For KDP, many authors say that the 30% is worth it because the volume of their Amazon sales dwarfs all other-channel sales combined. Some relatively famous sci-fi authors have said that about 90% of the sales of their self-published works were through Amazon.)