  Recent discoveries of a significant population of bright galaxies at cosmic
dawn $\left(z \gtrsim 10\right)$ have enabled critical tests of cosmological
galaxy formation models. In particular, the bright end of the galaxy UV
luminosity function (UVLF) appears higher than predicted by many models. Using
approximately 25,000 galaxy snapshots at $8 \leq z \leq 12$ in a suite of
FIRE-2 cosmological "zoom-in'' simulations from the Feedback in Realistic
Environments (FIRE) project, we show that the observed abundance of UV-bright
galaxies at cosmic dawn is reproduced in these simulations with a multi-channel
implementation of standard stellar feedback processes, without any fine-tuning.
Notably, we find no need to invoke previously suggested modifications such as a
non-standard cosmology, a top-heavy stellar initial mass function, or a
strongly enhanced star formation efficiency. We contrast the UVLFs predicted by
bursty star formation in these original simulations to those derived from star
formation histories (SFHs) smoothed over prescribed timescales (e.g., 100 Myr).
The comparison demonstrates that the strongly time-variable SFHs predicted by
the FIRE simulations play a key role in correctly reproducing the observed,
bright-end UVLFs at cosmic dawn: the bursty SFHs induce order-or-magnitude
changes in the abundance of UV-bright ($M_\mathrm{UV} \lesssim -20$) galaxies
at $z \gtrsim 10$. The predicted bright-end UVLFs are consistent with both the
spectroscopically confirmed population and the photometrically selected
candidates. We also find good agreement between the predicted and
observationally inferred integrated UV luminosity densities, which evolve more
weakly with redshift in FIRE than suggested by some other models.
