Depends on what you consider a good ROI. By auto-voting you can get a ROI in the tens of percent. But that is just the ROI in terms of STEEM. What you as an investor should really care about is your profits in fiat. If everyone engages in abusive behavior and you are only slightly better at than others, you are likely to be losing money anyway. Therefore, it makes perfect sense for you to support anti-abuse projects to protect your investment.