Whenever the term "bottomless pit" is used, the imagery is that of a wide deep dark hole that cannot be filled nor can the bottom be seen.
As much as bottomless pits may not exists, or at least not known to exist yet, the term bottomless pit is often used as a metaphor.
It is used to express, and maybe even to exaggerate, the peculiar characteristic of something or a person.
When used on a person, it expresses the inexhaustible yearning or demands like having possessions, wealth, attention and usually it is not that edifying.
In the 1st reading, St. Paul warns that religion should not be used to make a profit.
He goes on to say that we brought nothing into this world, and we can take nothing out of it.
And people who long to be rich or are like bottomless pits for worldly desires get trapped into all sorts of foolish and dangerous ambitions which eventually plunge them into ruin and destruction.
We may desire for more than food, clothing and shelter, but let us be contented with that.
More essentially is that we desire for God's blessings and protection so that we can experience God's providence here in this world, and eventually be granted salvation and eternal life in the next.