That does not matter as it has given a huge push to crypto ROI as many projects have generated ROI on the tune of 400 percent.
The ROI you talk about in these Defi projects is for the investors that made the most of the pump, 400% is too good to be true for a ROI for a project, when you see projects that offer ROI as high as that, it's a pump and dump coin that will end up a scam with losses for the investors. Uniswap is just one of the many Defi projects that will pump high and dump very fast.
Why would people blame uniswap for this?
People always blame the projects and call them scam when this happens, but on a second thought, the investors like the one in the op are to be blamed actually, not the pump and dump projects, many of the investors prolly invested in Ico and Ieo, and have experienced all these hype before, but they still get caught up in the Defi hype and lose their money again.