I don't get why people are upset or surprised about that. Did they think a frontend like DTube pays for itself? Someone has to pay for all the GPUs to do the video conversion and the storage space for all the video formats for example. Developers also don't work for free. If you don't pay them or pay them well they will leave this project and do other things like we just saw recently. What you want is a permanent staff of developers or things won't progress as fast as they should be.
But hey, since DTube is completely open source I invite all the boycotters to build their own fork, which they can then host absolutely for free.