They can because they think they can

 From Aeneid by Virgil, Book V, 151-243, The Boat Race:

But Mnesthus, delighted, and made eager by his success,
with a swift play of oars, and a prayer to the winds.
heads for home waters and courses the open sea,
as a dove, whose nest and sweet chicks are hidden
among the rocks, suddenly startled from some hollow,
takes flight for the fields, frightened from her cover,
and beats her wings loudly, but soon gliding in still air
skims her clear path, barely moving her swift pinions:
in this way Mnestheus and the Sea-Dragon herself furrow
the final stretch of water in flight, and her impetus
alone, carries her on her winged path. Firstly
he leaves Segestus behind struggling on the raised rock
then in shoal water, calling vainly for help,
and learning how to race with shattered oars.
Then he overhauls Gyas and the Chimaera’s huge bulk:
which, deprived of her helmsman now, gives way.
Now Cloanthus alone is left ahead, near to the finish,
Mnestheus heads for him and chases closely
exerting all his powers. Then indeed the shouts redouble,
and together all enthusiastically urge on the pursuer.
The former crew are unhappy lest they fail to keep
the honour that is theirs and the glory already
in their possession, and would sell their lives for fame.
the latter feed on success: they can because they think they can.
And with their prow alongside they might have snatched the prize,
if Cleanthus had not stretched out his hands over the sea
and poured out his prayers, and called to the gods in longing.
“Gods, whose empire is the ocean, whose waters I course,
On shore, I will gladly set a snow-white bull
before your altars, in payment of my vows,
throw the entrailsinto the saltwater, and pour out pure wine.”
He spoke, and all the Nereids, Phorcus’s choir, and virgin Panopea,
heard him in the wave’s depths, and father Portunus drove him
on his track, with his great hand: the ship ran to shore, swifter
than south wind or flying arrow, and plunged into the deep harbour.