Is even Buddhahood itself a short straw next to material wealth and pleasure and fame? Is even Buddhahood itself a short straw next to material wealth and pleasure and fame? The Buddha could have been a wheel turning monarch, and was in deed born a prince. So perhaps his decision isn't all that confusing for the rest of the world.
Is even a small degree of enlightenment preferable to unparalleled wealth and power, or are they in fact incomparable?

Put another way, what does your karma have to be to be born as a prince, as compared to e.g. the first jana?
Not just complete enlightenment. The Buddha taught that even the fruit of stream entry (the first stage of enlightenment, incomplete) exceeds sole dominion over the Earth and lordship over all worlds.
From Dhammapada 178:

Sole dominion over the earth,
going to heaven,
lordship over all worlds:
the fruit of stream-entry
excels them.

The commentary for this verse:

The Story of Kala, son of Anathapindika
While residing at the Jetavana monastery, the Buddha uttered Verse
(178) of this book, with reference to Kala, son of Anathapindika, the
well renowned rich man of Savatthi.
Kala, son of Anathapindika, always kept away whenever the Buddha and
his company of bhikkhus came to their house. Anathapindika was afraid
that if his son kept on behaving in this way, he would be reborn in
one of the lower worlds (apayas). So, he enticed his son with the
promise of money. He promised to give one hundred if the youth
consented to go to the monastery and keep sabbath for one day. So, the
youth went to the monastery and returned home early the next day,
without listening to any religious discourses. His father offered him
rice gruel, but instead of taking his food, he first demanded to have
the money.
The next day, the father said to his son, &quot;My son, if you learn a
stanza of the Text from the Buddha I will give you one thousand on
your return.&quot; So, Kala went to the monastery again, and told the
Buddha that he wanted to learn something. The Buddha gave him a short
stanza to learn by heart; at the same time he willed that the youth
would not be able to memorize it. Thus, the youth had to repeat a
single stanza many times, but because he had to repeat it so many
times, in the end, he came to perceive the full meaning of the Dhamma
and attained Sotapatti Fruition.
Early on the next morning, he followed the Buddha and the bhikkhus to
his own house. But on that day, he was silently wishing, &quot;I wish my
father would not give me the one thousand in the presence of the
Buddha. I do not wish the Buddha to know that I kept the sabbath just
for the sake of money.&quot; His father offered rice gruel to the Buddha
and the bhikkhus, and also to him. Then, his father brought one
thousand, and told Kala to take the money but surprisingly he refused.
His father pressed him to take it, but he still refused. Then,
Anathapindika said to the Buddha, &quot;Venerable Sir, my son is quite
changed; he now behaves in a very pleasant manner.&quot; Then he related to
the Buddha how he had enticed the youth with money to go to the
monastery and keep sabbath and to learn some religious texts. To him
the Buddha replied, &quot;Anathapindika! Today, your son has attained
Sotapatti Fruition, which is much better than the riches of the
Universal Monarch or that of the devas or that of the brahmas.&quot;
Then the Buddha spoke in verse as follows:
Verse 178: Far better
than sovereignty over the earth, or far better than going to the
abodes of the devas, or far better than ruling supreme over the entire
universe, is (the attainment of) Sotapatti Fruition.