From the plugin site:
Like most other apps on STEEM, including esteem, dtube, dsound, dmania, utopian and zappl to name a few, we intend to use benefactor rewards to help run SteemPress. The benefactor rewards is currently set to 10%. In comparison, Dtube and Utopian both take 25% benefactor rewards while Zappl takes 15%.
You seem to be taking 15%. And 2/3 of it is going to your personal accounts rather than the project's account, which seems like it ought to be explained at the very least.
And dtube and utopian no longer take 25% so there is that.
Woops, I forgot to update that thanks for the heads up !
As for why the money goes in our personal accounts is because we simply need to eat. In two months, we'll both leave our day jobs to work full time on steempress and steem.
Also note that the beneficiaries are not the biggest part of the revenue, curation rewards are (like 2-3x more according to my estimates), so most of the money still goes to powering up the account.