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
If you are always watching the market and you will know if this time the investors are experienced to determine which is good or bad defi. It's about the non defi project that tries to follow the trend to release their defi but I think if they were going out from their capabilities and comfort zone.