“A burning passion coupled with absolute detachment is the key to
–Mahatma Gandhi (1869–1948)
You can draw value from a naysayer or cynic by remaining objective and positive in your thinking (yes, it can be tough).
Occasionally, they’ll point out valid hurdles or challenges you haven’t seen (even if they present it like an @ss). With their help, if you can remain objective/detached (and keep your ego in check), you’ll have a better chance of getting something valuable from the interaction.
Stay objective. Be no ego. Get value. (Seriously)