Well, it's look likes a fomo to me because it'll vanish just like other trends when more public will attract into Defi and get low reward as it's the main point for all the newcomers who get interest into defi. Also i see many of the well reputed Top crypto projects are shifting to Defi catagory. Recently, Tomochain get the Defi tag on CMC and all people get in fomo and buy tomo.As a result, tomo get an instant pump. But the major coins won't be effected , imo.
You absolutely right the FOMO. Greed is always comes in hand with trend. And trend will always expired once there are too many participants. If the capital shift did happen, the capital will eventually shifted back to major coins, especially Bitcoin when the trend is dying. Bitcoin is still the most decentralized and secured cryptocurrency.