[dahdum]

You're right, but that's only the case right now. Incredible effort has been and continues to be made on making PoS secure, scalable, and distributed.

I'm not aware of any insurmountable problems having been found. With Eth2.0 steadily approaching launch and other networks in various stages of progression, it seems increasingly unlikely we'll find one.

[aeternum]

The insurmountable problem is that a user cannot tell which is the 'real' fork of a PoS chain without some kind of sidechannel information.