Please don't forget transaction fees:

The network seems to give out 8 coins per day for a masternode, plus transaction fees. 

For those who put out masternodes early you got lucky for reaping all the transaction fees from the swap; but now there are more masternodes so the transaction fees are going to decrease until there are more nodes on the network.

Where your masternode is located also determines what kind of profits you get from the transaction fees.

I have three masternodes - each located in a financial hotspot around the world.

The VPS host providers network can also determine what kind of profits you get.

Some vps hosters are cheap but how many users are on their networks? Other VPS servers might be more expensive but their networks might be more profitable.

All these things go into how many coins you get per day.