The fact that the Athenians lost so few men was the exact reason the Spartans were so surprised when they arrived at the battlefield. Mainly because they thought the Athenians to be a bunch of philosophers and not warriors.

From memory, I think the sources estimate the Persians to be about 28000.

Final payback was arguably by Persia. Persia learnt to play Greek against Greek, in the Pelopponesian War funding repeated rebuldings of the Spartan navy until that actually became a viable force (who would have thought ?) It was Athens that ultimately lost and to a militarised ethnic-group supremacist state that was the antithesis of democratic ideals. Athens never quite regained its old glory after that.

While the exact size of the Persian army in the first Persian War is
truly unknown, what is known that the Persians considered
Marathon more of a set back than a defeat. They were able to
board their ships. Since the Athenian Army was at Marathon, the
Persians set sail to Athens to burn it to the ground. The Greeks
realized what was happening and the entire Army ran to Athens
and got there ahead of the Persians. King Darius of Persia seeing
the Greek Army waiting, turned around and went back to Persia;
humiliated but with his Navy and Army bloodied but intact.

The Athenian Army was well trained and practiced running long
distances in full armor. The Greek infantry was heavily armored
in comparison to the Persians who used wicker shields little to no
armor. Each Athenian youth was required serve two years in the
army undergoing one year military training doing garrison duty
before being considers being sufficiently trained for combat. After
that, each male was subject to recall into the army until he
reached the age of 60.

Ten years later in 481 BC, King Darius was dead and his son, King
Xerxes invaded Greece again to avenge his father’s humiliation
and to teach the Greeks a lesson. The Persian Army is reported to
exceed 1,000,000 men but more likely was between 100,000 to
200,000 men. Three major battles occurred in this war. The
first was at Thermopylae where a vastly inferior Greek army
stalled the might of Persia for days before King Xerxes defeated
the Greeks. While a defeat for Greece, the heroism of its soldiers
inspired and united the Greeks. The second major battle in the
second Persian War was a naval battle at Salamis where the
Greek navy destroyed the Persian navy in perhaps the bloodiest
naval engagement in all history (modern historians estimate
that as many as 30,000 died on both sides). Without control of
the seas needed to support his huge army, the Persian position in
Greece was no longer supportable and the Persian Army was
destroyed at the Battle of Plataea in 479BC. Years later, in 333
BC Alexandria the Great initiated Greece’s third war with Persia
ending Persia’s presence as a world power for all times.