Come on mate talk about crypto and forget about the stock market while you are here. We all know how much manipulated the stock market is - not saying that crypto is not, but at least crypto is not that influenced by Politics. Though some FUDstars will argue that even Politics and Zombie invasion have things to do with crypto but lets forget that for now.

OP, highest ROI does not come from investing in coins for a few days. It comes from patience and perseverance. Look at the price charts of bitcoin and ethereum (at least) and see the ROI of these coins and the ROI period for that specific rise/fall. Bitcoin have come from 100$ at one time to 6k+$ today even in the bear market. Do you consider that as "High" ROI? You may not because the term "High" is again relative.