To my mind, the poll looks like a trick question, because I've always understood 'rich' to be a description of wealth, not of income.
It's very hard to pin down precisely, but I suspect if I had to attempt a precise definition of the word, it'd be something like
Code:
int houseCost = GetTypicalCostOfHouseBigEnoughForYourFamily();
bool isRich = (totalAssets - houseCost - totalLiabilities) > 1000000;
In other words, add up the value of everything you own including your house(s) if you own any. Subtract from that the average cost of a reasonable house in your locality that's big enough for your family, and any debts you have. If the result is more than a million quid, then it would seem reasonable to count yourself as being 'rich'.
Note that there are no value judgements implied here. I find it sad that in some circles, 'rich' has almost become a term of contempt - when of course in reality there is absolutely nothing wrong in principle with being rich.