Let $\Omega = \{0,1\}$ and $X: \Omega \rightarrow \{0,1\}$ be a random variable s.t. $X = id$ with $E[X] = 0.5$ (i.e., $P(0) = 0.5 = P(1)$).
Let $X_1$, $X_2$, $\ldots$ be a sequence of i.i.d. random variables with $E[X_1] = E[X_2] = \ldots = 0.5 = E[X]$. In particular, let each of $X_i = id = X$.
Assertion: It seems to me necessarily the case that
$$ \overline{X}_n = {1 \over n} (X_1 + \ldots + X_n) = X $$
This is since
$$ {1 \over n} (X_1(0) + \ldots + X_n(0)) = {1 \over n}0 = 0 = X(0) $$
and
$$ {1 \over n} (X_1(1) + \ldots + X_n(1)) = {1 \over n}n = 1 = X(1) $$
But this means that as $n \rightarrow \infty$, it is not the case that $\overline{X}_n \to E[X] = 0.5$.
Question: How is this not a counter-example to the law of large numbers?
The law of large numbers applies to independent identically distributed random variables, whereas you're trying to apply it to identical random variables, which are not independent.