Totally understandable. But you should keep in mind there are other options open to you. You can have a Steam page, don't sell it there (yet) and sell it here. Give the key now and have people be able to play on Steam now. But because it isn't released/purchasable on Steam yet - no reviews will be allowed. This is how I operated the beta for our game, and many other titles do this too. Then release the game on Steam when you want/1.0. And you are generating buzz over on Steam the whole way there and getting folks to wishlist it, talk about it, etc.
As far as the 30% cut - I get it, I really do - but the exposure on Steam is manyfold compared to any exposure you are gonna get here, or anywhere else where the digital distribution platform cut is significantly less. Some consider that cut simply the cost of better marketing. Sure, it's not amazing marketing, but the price isn't all that high either (good marketing is crazy expensive anyways). Bottom line is that you will factually reach more folks on Steam. And as an indie dev with an indie project - you likely need all the help and exposure you can get. More is more, and it probably still isn't enough.