Neither Einstein nor Hitler were orders of magnitudes greater intelligence than the average human- Albert was smart, but nowhere near the potential of AI.
Neither Einstein nor Hitler could process data from all around the world from millions of inputs at the same time.
Einstein and Hitler were both mortal and had a finite life span.
However, even though both Einstein and Hitler were singular humans with limited capabilities and lifespans that could not begin to have the potential impact of something like AI, there is a "meta" version of both personas that was somewhat inspired mythically by the actual humans, that continues to live and influence people today. This meta-Einstein and meta-Hitler are un-embodied ideas which are no longer constrained by mortal limits and you might argue are actually more powerful today than they were in when their namesakes were alive because there are millions more people supporting the mystique behind them and often even operating on behalf of these meta-beings (aka, the idea of the person not to be confused with that person's actual ideas).
These meta-beings (anthropormophizing a set of ideas to be represented by a popular figure) can even be extrapolated from an entity who may or may not of even actually existed in real life (e.g., meta-Jesus or perhaps AI).
To borrow some contemporary lingo, once created, key to the power of this meta-being (which is really an un-embodied idea even though it might be "named" after someone that inspired it) is dependent on if it "goes viral" or not. Unfortunately, "going-viral" is almost an autonomic reflex of our societal-organism over which we have little conscious control. The analogy of a "virus" is pretty good since the idea is not a real organism (or person), it depends on the societal-organism's infrastructure for reproduction and propagation. Once the "virus" takes over part of the infrastructure, the influence if as large (or even larger due to multiplicative effects) as the infrastructure it overruns.
The immunity response to "bad-viruses" of our societal-organism, is not unlike a real-organism's immunity response. If it can remember an idea is bad, the societal-organism is better at containing it before it gets out of hand. If the idea has mutated a bit, or the response would create some complicated inconsistencies (e.g, good for some parts of the organism, bad for some parts), the immunity has a hard time mounting any defense and the virus is more likely to get a permanent foothold or even take over.
Nobody knows if AI is a "good-virus" or a "bad-virus" with respect to our societal-organism, but I'll go out on a limb and say it's probably good for some, bad for others which mean the if it ever goes viral, it will be very hard for our society "immunity" to stop it. Let's hope it's a good idea... Our society's immune system has yet to kill meta-Hitler probably because some of the ideas represented by meta-Hitler are potentially good for more than a small part of the societal organism.