It's just a 51% attack with extra steps. PoW requires that you do the work. Making a big long fake chain with higher difficulty than the existing chain requir

It's just a 51% attack with extra steps. PoW requires that you do the work. Making a big long fake chain with higher difficulty than the existing chain requires expending even more resources than the existing network. Not to mention you have to keep updating your fake chain every time a legit block gets accepted because all of the hashes will change. The idea is garbage.