Spagghetification occurs when the gravitational potential energy on the side of the grain of sand closer to the center of the black hole is much larger than the potential energy on the other side. The gradient in potential energy across the grain of sand leads to a force, and if this force is large enough it will be larger than the forces holding the grain of sand together.
For simplicity, let's assume a non-spinning black hole of mass $M$.
The potential energy on the "near side" of the grain of sand, at a distance $r$ from the black hole singularity, is
$$
U_1 = \frac{GM}{r}
$$
The potential energy on the "far side" is
$$
U_2 = \frac{GM}{r + d}
$$
where $d$ is the diameter of the grain of sand.
Now when $r \gg d$, it is true that $U_1 - U_2 \approx 0$. This is where your intuition likely comes in.
However, if we are imagining a grain of sand falling into a black hole and hitting the singularity, then we are ultimately imagining $r$ going to zero. So we cannot assume $r \gg d$.
In fact, we have
$$
U_1 - U_2 = \frac{GM}{r}\left(1 - \frac{r}{r+d}\right) = \frac{GM}{r}\left(\frac{d}{r+d}\right)
$$
As $r\rightarrow 0$, this energy difference will become arbitrarily large. So as $r$ becomes small enough, inevitably the tidal force ripping apart the grain of sand will become larger than whatever (electromagnetic) forces hold it together.
We expect spaghettification to happen to any finite size particle -- sand grains, hydrogen, neutrons, etc.
There are a few caveats, because most physicists don't expect general relativity to be a complete theory that tells us what happens near the singularity of a black hole. Probably we need a quantum theory of gravity to really answer these questions.
When you start to get to distances $r$ of order a Planck length from the singularity, most physicists would agree that quantum gravity will become important, so the predictions of GR are no longer a good guide. However, there are also some speculative ideas that even when $r$ is of order the horizon of the black hole, general relativity breaks down. So, a final word of warning may be that since we cannot do any experiments to really see what happens to grains of sand in a black hole, we should be humble about saying exactly what will or won't happen.