It's still all about the same mistakes that investors use to do over and over again, the lack of doing good research is what making many invest money on stupid projects, now that DeFi projects are doing big many scammers will definitely bring their scam projects to lure inexperienced investors
Yes, its gonna happen because a lack of research before investing money in a newer project could vanish your capital. Now there are major chances many people would use Defi as a weapon to scam people and investors with a lack of research gonna thinks Defi is good and become a victim of a scam.