Michael Dukakis was a Democrat candidate running for President in 1988. He had previously been criticized as being soft on national defense, so in September of that year he orchestrated a photo op in an M1 Abrams tank meant to toughen up his image.
The public found the image of Dukakis in the oversized safety helmet comical, and the photo op had the opposite of the intended effect of making him look tough. So much so that his opponent, George H.W. Bush used footage of Dukakis' tank ride in his own advertisements.
Is his helmet "oversized"? It just looks like it has built-in hearing protection and headphones, which makes sense for use in a tank.
The general public tends to make snap impressions. Even if this was how a CVC looked on a real tanker, people weren't looking at them side by side. The photo op was a very transparent attempt to "look tough" by someone who simply didn't, and probably shouldn't have tried to do so.
That aside, his liner at least does seem about a size too large. The liner is massive and because of that, the CVC shell's lip is about even with the top of his head. As opposed to a properly fitting CVC, the lip of the shell just about touching the top of the eyebrows:
Finally, for some reason Dukakis also has the chinstrap hanging off of his lower lip instead of his chin, which isn't helping.