Let $X$ be a Banach space. Or say, even just a normed linear space. Let $N \in \mathbb N$.
Does there exist $x \in X $ with $\|x\| \ge N$?
If $X$ is a Banach space then its unit ball is also a Banach space so the answer should be no. But in the proof of the Alaoglu theorem it is used that if we let $D_x = B(0,\|x\|) \subseteq \mathbb C$ then $\mathbb C = \bigcup_{x \in X} D_x$ and this seems to me requires that for every $N$ there is $x$ with $\|x\|\ge N$.
Let $x\neq 0$ be any non-zero element, so that $\lVert x \rVert\neq 0$. Let $y=\dfrac{N}{\lVert x \rVert}x$. Then $\lVert y \rVert = N$. Right?