all good, but we dont know the ROI for being masternode ...
Sonm is a non-mineable cryptocurrency.
On the basis of that, ROI will depends on the network usage. The more deals(txs) will going through network, the more roi(fee) you will get. With the increasing popularity of sonm network ROI would be a huge. However, it's clear that this won't happen overnight.
The buying of enough SONM for a master node is some kind of risk now. It will worth the buying if SONM will succeed in the future, while if it is not popular the investment will be in a loss.