Why didn't Canadians ever try to overthrow British rule?

Some Canadians did side with the revolutionaries in the American colonies, but it was not enough to make a substantial difference. There is a common misconception in discussions about the Revolutionary War that Patriots made up a sizable majority of colonists. The Loyalists and Patriots combined likely made up a bit less than half of the colonists in the 13 colonies, with the majorities of colonists remaining neutral. The Loyalists largely joined English armies or fled the colonies. New England Loyalists that fled generally went to Canada, with about 100,000 of them doing so.
Whether a similar percentage of Loyalists, Patriots, and Neutralists existed in the Canadian colonies is unclear, however, both the Patriots and the British had difficulty raising a significant number of troops in Canada, which lends credence to the idea that Neutralists were again in the minority.
American Patriots also engaged in several self-defeating actions in trying to woo Canadians to their side. The Nova Scotians were closely allied with New England colonists and had a group that would likely have joined the Patriots. However, this group was rebuffed by both Washington and the Continental Congress because the timing was bad. Washington was worried about the British fleet, and he had just suffered a defeat in an attempted invasion of Quebec and the Continental Congress was drafting the Declaration of Independence. There were also insufficient resources to divert to Canada.
American privateers also operated against Nova Scotian ships, largely because they could not attack the British navy. The privateers did not discriminate between targets in order to single out Loyalists. This likely drove some Neutralists into the Loyalist camp and disenchanted many Patriots. The invasion of Quebec was also problematic because the substantial defeat likely disenchanted Canadian Patriots who might otherwise have joined. The defeat made the Continental Army appear under-supplied, under-manned, and poorly led. This, combined with the discrimination against Catholics and the desire to impose English property law throughout the continent also likely cost the Patriots support from French Canadians, who would have been likely allies.
In summary, Canada likely had far more Neutralists than Loyalists or Patriots, much like the colonies. The American Patriots did a poor job of recruiting and supporting Canadian colonists. These two things likely combined to prevent Canada from seeking to overthrow English rule. With regard to questions of later revolution, it is important to remember that successful revolutions are quite rare in history, especially since the industrial revolution. Without significant complaints among a large proportion of Canadians, it is unlikely that such a rare remedy would have been widely sought, though smaller groups may have taken up actions.