First, if I have product, I decide where to sell it. If I want to give away, it is my decission. If I decide my super tetris clone is worth $500 - nothing will stop me. That how much valuable is to me. If I decide I don't want to put 1/3 of my crew on starving wage, I need to keep some standards. this mean: don'e sell yourself cheap and don't get yourself robbed.
Second, Steam is more popular and go-to store. The other name for it is 'monopoly'. Thanks to epic now I have choice where to sell my game. Thanks to that Steam is loosing a bit ppopularity, and epic is gaining. I'm happy withy that because that's the only way to reduce steam tax.
So I'm absolutely fine to take initial hit even if Epic make it sweeter knoing this will improve the competition. Agreeing to unreasonable cut is just living with a prisoner dilema. People who do not care about competition and actively insisting to use a monopolist store are the problem, not people who wants to be part of the market.
You have a choice - and I have a choice. I do not have make a choice you want me to make. And that's completly fine. go somewhere else. Customer (on both sides) are right