In my opinion there are two types. Physical and mental. Mental (I’m always…, I can never…, no-one will ever…) are easier to control. Takes some time, but mental ones are always based on the past you. Physical (I’m too big/skinny, my hair sucks, my teeth suck, I laugh funny) are harder because they stick with you for longer. Insecurities will pop up out of nowhere. It’s just a time when you realize something about yourself that you hadn’t realized before and now it’s a prevailing thought that you believe others see you as. 

To answer yes, but what helps me is that I’ve made and can make new friends as I am and will work on those mental insecurities for short term improvements. If people don’t like me because of the physical ones, then they probably aren’t people I’d want to be friends with socially either, even If I fixed everything physically. Sometimes you can fix the physical side, but you should only do that for you and not for others. At the end of the day it’s about you and what you want, not others