How is a Bimodal distribution platykurtic? I am trying to understand how the distribution on the right is platykurtic? I learned that platykurtic indicates lighter and thinner tails and from what it looks like, the bimodal distribution, with a superimposed normal curve, seems to have a lot more values in the tails?
Is it light-tailed by the fact that each mode is skewed? Thank you.


While the incorrect "peakedness" interpretation of kurtosis is finally fading away, it has been replaced by other, slightly less egregious misinterpretations. One is that high kurtosis means "a lot of data in the tails." This may have been started by Balanda and MacGillivray, who "defined" kurtosis "vaguely as the location- and scale-free movement of probability mass from the shoulders of a distribution into its center and tails".
This "interpretation" is a reversal of the implication in the Finucan result, which proves that as mass moves away from the "shoulders" to the center and tails, then kurtosis increases. (Incidentally, there is no contradiction here in the bimodal case because there is no mass in the center).  Unfortunately, the Finucan conditions do not tell you what larger kurtosis implies about the distribution.  To infer that larger kurtosis implies "more mass in the tails" is akin to stating "well, I know all bears are mammals, so it must be the case that all mammals are bears."
For a simple counterexample of a family of probability distributions where kurtosis tends to infinity, but tail mass decreases, see here: https://math.stackexchange.com/a/2510884/472987
Rather than "mass in the tails," kurtosis precisely measures tail leverage, a combination of mass and extension.  Greater extension implies greater leverage, even with little mass (Archimedes boasted that he could move the earth with a long enough lever). A single outlier, sufficiently distant from the pack of data, is enough to create great leverage. Thus, while a comment above seemed to say that kurtosis is "distorted" by outliers (suggesting a nod to the incorrect "peakedness" definition?), the more correct statement is that kurtosis measures outliers.
While outliers are sometimes defined as "mistakes," I am referring to them here as "rare, extreme values." The two-point equiprobable bimodal distribution is the least outlier-prone distribution in the universe of distributions.  That is to say, it has the least tail leverage.
Besides my 2014 paper "Kurtosis as Peakedness: 1905-2014. R.I.P.," here are some posts that explain the precise nature of the "tail leverage" meaning of kurtosis.
https://stats.stackexchange.com/a/532055/102879
https://stats.stackexchange.com/a/481022/102879
