The 50% ROI is fairly high but it won't be if inflation gets hold of it and strangles the price. It's also very early to tell and the graph is so over the place I don't know what to think right now.
Theres a max supply of 21 million, so inflation long term is capped and maxed out it's actually deflationary. I think the 50 percent ROI is just to award the block reward more of the pie to the masternode holders from the miners
Overall I think this is all fine and healthy. Masternode holders care more about the network and are the long term holders. Miners will just dump their coins the same day and get whatever btc they can get out of it.
Yep, well explained. It's definitely the masternode owners who have a serious long-term interest in the network.