I get incredibly jealous when i see someone taller than me, even though i am 6'6 and can easily reach 6'8 depending on what shoes i wear, any advice?

Jealousy: For some reasons you are feeling insecure about your self worth, as your height is above most in the world. Consult a clinical psychologist who could help you increase your self worth and uncover the origins of your discomfort. Best.

Get therapy: You would probably benefit the most from either counseling or therapy. This appears to be a psychological issue probably regarding your identification with masculinity and unchecked insecurities. Life has a lot of numbers in it and you are not going to always going to be at the top of the leaderboard! i hope you get some help when you get a chance! stay safe!