The language of implication is often used in common speech, but usually to mean
something rather different from implication in mathematical logic.
In one sense, people may attach a causal relationship or at least a
positive correlation between the clauses linked
by "if". For example, if you have high blood pressure, your life expectancy
is less than the average person's. There is a positive correlation between
high blood pressure and low life expectancy.
That is, there is a tendency to interpret "if A then B" as "A tends to cause B"
or "observing A makes B more likely."
Neither of the implications fits either of these interpretations.
For implication (2), however, we have to use some knowledge of the
real world to come to this conclusion; that is, it seems obvious
(based on what we know about how the moon came to be, and how Bill Gates
gained his wealth)
that the composition of the moon is not predicted in any way by how much
wealth Bill Gates has.
For implication (1), we do not need to know anything about
cosmology or cheese or even to know who
Bill Gates is to reject causality or correlation; we merely need to
know that "rich" is the opposite of "poor".
Being poor cannot cause you to be rich, and it is not correlated with being rich.
Alternatively, there is one common way in which the language of implication
is used when the antecedent is believed to be false, namely, to emphasize
how sure one is that the antecedent is false.
For example, a common English idiom to express disbelief in the
proposition that Bill Gates is poor is,
"If Bill Gates is poor then I'm a monkey's uncle."
Since I am not a monkey's uncle
(which the listener hopefully will accept as obviously true without question),
the statement "Bill Gates is poor", combined with my implication,
contradicts a known true fact and therefore is rejected.
A variant of this is,
"If Bill Gates is poor then I'll eat my hat."
The usual connotation of this is that it would be very unpleasant for me
to have to eat my hat, so making this statement shows that I am quite
confident Bill Gates is not poor (since otherwise I would be taking some
risk of having to eat my hat later, in case it is shown that he is poor).
Implication (2) can be taken as yet another variant of this same idiom,
namely, we use an absurdly false consequent
(or in the eat-my-hat variant, one the speaker presumably hopes is false)
in order to emphasize how unlikely the antecedent is to be true.
Everyone knows the moon is not actually made of cheese
(Wallace and Gromit notwithstanding), so clearly this implication says
Bill Gates is not poor. And indeed Bill Gates is not poor.
In this sense, implication (2) is absurd but true in common,
On the other hand, since Bill Gates is rich, there is not even a hope
that the consequent of implication (1) is false.
Implication (1) thus does not fit the pattern of this common idiom at all,
and is not recognized as a non-mathematical way of saying that
Bill Gates is not poor. To ascribe that meaning to it, one has to work
through details of mathematical logic that are not part of our
common intuition about the English language.