So fuji, the obvious solution for that problem is for Toronto to separate not just from Ontario, but from Canada also, and be its own country. It would be a city-state, like Monaco.
With respect to your tax analysis, you could be right, but I think it is more complex than that. Your reasoning makes sense on the high side, in that the top tier pay way more tax per person. But the bottom tier consume way more. The real dregs of society that are constantly in contact with the police, social services, childrens aid, etc, cost a vast amount. 100 people in Toronto might include a couple of super earners in the 100, where Bruce was 100 middle income earners. But the Toronto 100 would also include a few who consumed a lot of resources. Perhaps some of those dregs rode the bus in from Bruce, but likely so did some of the super earners too.
And Toronto would not be cold-hearted and keep out the dregs, Toronto is way more socialist than that, they would be taking in all they could get their hands on, and over-taxing the super earners, who would leave. Imagine David Miller with the power to set income tax rates.