It's not a scam because it does make you code faster even if you must review everything and possibly correct (either manually or via instruction) some things.

As far as hallucinations go, it is useful as long as its reliability is above a certain (high) percentage.

I actually tried to come up with a "perceived utility" function as a function of reliability: U(r)=Umax ⋅e^(−k(100−r)^n) with k=0.025 and n=1.5 is the best I came up with, plotted here: https://imgur.com/gallery/reliability-utility-function-u-r-u...