LOL on the entire 'ROI' discussion. It's not that important, but the term is obviously incorrectly used for Dash masternodes and staking projects for example.
ROI applies to anyone with 1 Dash or 10 masternodes. It is your return on your invested capital, thus in USD/EURO/... It can be positive or negative. It can be -98% or +10,000%.
Dash masternodes (and staking) coins give you a return or reward which is not ROI. Currently the masternode service reward is around 6%, but that is not 6% ROI. If that were true, Dash would be a scam. Ergo, Dash should never apply the ROI term when it comes to Dash masternodes.