Nice presentition but there's a big missing part in the ROI.. quoted from the link

please keep in mind that there will only be a relatively small number of validators that receive the lion's share of the votes, so this 375k SPS / month will be split among a small group of accounts

To get 1/2000th of the rewards, you need to have 1/2000th of the staked SPS voting for you, which implies you either own it (about 20k USD worth of SPS), or have alot of influence and have people voting for you.