Just to share my own point of view of why we tend to fade away, as I'm noticing on myself - okay, I'm still here, though not nearly as often as during the initial months full of novelty and excitement.
Do we tend to get busy with many other things all of a sudden? Maybe. Though for me I'd say I used to spend way more time on Steemit at first than would have been sustainable in the long run. Now I'm catching up on other things I'd postponed in favor of reading / writing posts, and as a result I'm not on as much as I'd like to be. Ideally, I want to find a good balance because I don't want to stop steeming. I can imagine many other steemians to feel similar.
Yes steemit does compete for time with everything else in life. For me steemit at the moment is an enjoyable and informative hobby. I don't use any other social media, nor do I have a TV or Netflix etc, so steemit fills that time slot. But I can quite see how it might need to be pushed aside from time to time to let life take priority.