The overwhelming majority of people don't care about digital privacy because the cost is opaque to them.
Also, telemetry when done right isn't "spying". Again, it is anonymized and used to see, for example, where the hot paths and paper cuts in applications are.
if it has telemetry, then it is a tool the customer buys, that also has the function of listening and reporting to others, how it is being used.
you want to sell it - no problem. but tell the customer, "look, this is bugged, and it's going to tell me what you are doing. but it's a great product." anything with opt-out telemetry needs a big version of that warning on the top of the page.
personally i am not a buyer. but that's my preference.
The “Firefox Problem” is that all the power users disable telemetry, so all the “cool” features that power users like (but never get used by “regular people”) get ignored or removed instead of improved because, according to the metrics, “nobody uses them”.
Knowing what (vulnerable) version of software a user is using transmitted in the clear was absolutely a part of the NSA monitoring error information from windows crash logs https://www.schneier.com/blog/archives/2017/08/nsa_collects_... - so forgive me if I do not trust the developer to know what makes me unsafe or not.
If you enable telemetry by default I will do my best to never use your product.