Bounty is just not as good source of income as it used to be a couple of years ago, that's the main reason. And many people are just tired of this boring activities I think, their motivation is too weak

I think the good times are around now. The reason that people got discouraged was because of ICO scam but now that ieo and already listed coins are beginning to come up, you might be lucky to own a very reputable coin. Anyway, giving up on something is not really the best thing to do.