Downvotes as are part of the system, and apart from some really malicious person and his friends who downvotes people unjustly,  most downvotes have been justified because of stolen content and all other things. 
Generally I just think the crypto market makes people saddened when it's the bear market, and they lose interest, when they could actually be accumulating.

I think life issues is the main thing.. some people just morph, their lives become different and they become less active