Defi stands for Decentralized Finance, that is to say it is developed to be entirely decentralized and hence out of the reach of the government and so on. Therefore going against its nature means it won't be called DeFi again and that alone will destroy a whole lot of things as people will lose interest. So the simple answer is, Defi can not be regulated and should not be regulated.
This idea of regulation is to curb scams in different levels, but what about those rushing after all these Defi projects how much research did they do? A good number went for hype.
So in my own opinion, regulation can't be in the same line with Defi because it will not work. Also, people should try and take caution by trying their best to study some of these projects as people holding major coins hardly worry.