Which cases? Is there mathematics of infinity that you're privy to that are unknown to mathematicians? Also I disagree that thinking about infinity is useful w

Which cases? Is there mathematics of infinity that you're privy to that are unknown to mathematicians? Also I disagree that thinking about infinity is useful when thinking about large numbers. That seems to me to be a fallacy. Any finite large number is inconsequential, and might as well be a 'small' number for any practical purposes, compared to any infinity.