Eventually every developer needs to be paid. And you want him to work hard to make your investment being worth 100x. You say he can mine himself, well, that's a different story. That has nothing to do with a proper payment for the work a dev does.
Dev have made an announcement about their first blockchain project - depository. In this depository they establised a fee that wallets holders need to pay to get depository box.
Makes sense as first and foremost everybody here wants the development to be healthily sustained over time. Only money can help with making that happen.