What is the appeal of watching really big streamers ?

I thought the appeal of watching streamers is the interactivity with the streamer through chats and the ability to directly support them through donations. But some big streamers like RDCworld has like 60K concurrent viewers, if you type in chat it's like talking to the void, and they defo don't need the 5 dollars donation I give. So it's like basically watching a youtube video but without the ability to fast forward.

So what gives.