The more dramatic Cancel Netflix movements have come from former subscribers who took issue with content that Netflix chose to put up rather than content that they chose to take down. However, canceling Netflix subscriptions can send a strong message that we weren't able to send as effectively when Fox canceled Firefly. To be fair, this isn't a problem unique to Netflix.
The result is that even shows with dedicated fanbases come down if that fanbase isn't large enough. One brand of Cancel Netflix protestors means to punish Netflix for removing shows that they enjoyed. As streaming services including Netflix turn to producing more of their own content, they can't afford to keep titles up forever. Rising rates and changing markets aside, there are those who quit Netflix for more impassioned reasons. However, more streaming services must also mean some watchers closing their Netflix accounts and signing up for other platforms. Netflix is certainly right about some people paying for more than one streaming service for the sake of differing exclusive and original content. A report for Q3 of 2020 specifically mentioned "the debut of Comcast's Peacock, which comes on the heels of the launch of HBO Max and Disney+." Quarterly reports to investors often get more specific. "The transition to streaming entertainment, with it's greater customer satisfaction, will mean growth for many services," the overview states.
The Netflix corporate overview plays this down to investors, as Netflix compares itself and rival HBO to cable's coexisting competitors ABC and NBC. While Netflix offers an alternative to cable, or "linear video" as Netflix calls it, there are more streaming services popping up all the time. If that was not enough, the company is not the only game in town. For one thing, Netflix often raises its prices. There are a lot of reasons why someone might quit Netflix.