A genius addict disproves the broader claim no more than does "it was cold today, therefore global warming is a hoax". The rule can be true yet still have notable exceptions throughout history.
There are "plenty" of cold days as well. Does that disprove global warming?
Not only is "plenty" not an objective quantity, but even an objectively large quantity is irrelevant if it's not a large percentage of the whole. 100k geniuses with addiction problems wouldn't disprove the rule if there are 1b people with addiction problems who are of below average intelligence.