Every crypto system gives incentives for participating in the network. Part of the participation in the NuBits system is to reward holding the coins at certain times if the supply has become too big and they don't want too many of the coins to hit the exchanges as sell orders.

I was surprised there was currently a reward that large for parking coins right now. There are 11,000,000 in circulation but 70,000,000 in existence. So it appears that a lot are currently parked which is looking pretty lucrative.

The main thing is the supply is increasing to counter act the demand. Instead of letting the price go parabolic when the demand shoots up the supply increases. If suddenly the supply out there is way up they have to incentivize holding so too much of it doesn't get dumped on the exchanges.

SmartCash incentivizes holding as well with the SmartNode and SmartRewards system but the rate of release is a predefined rate so it can suffer partially from too much supply hitting the markets and they don't have any mechanisms to maintain a certain price level on the upside or downside.

Bitconnect had multiple problems from multiple angles. First being there was no volatility software marking gains that they were reporting and paying out. Secondly the founders probably took hundreds of millions for themselves digging a deeper grave. And thirdly the pyramid refferal system had too many levels to be sustainable mathematically. the only reason it survived for that long was because the crypto market was going parabolic and so many people were joining in to keep it up during that time.