Is "troppo è come niente" an Italian proverb meaning "too much is like nothing"?
I'm Italian and honestly I've never heard of this, although if I had to guess then yes, it would mean something like "too much is like nothing".
Other proverbs with similar words are "il troppo stroppia" meaning "too much (of something) can be annoying" and "chi troppo vuole nulla stringe", meaning "who wants too much will get nothing". They are both much more famous proverbs about "troppo". I tried googling yours and I couldn't find anything of significance. Where did you find it?