I have to disagree with the last poster, who you are in high school IS who you will be 5 or 10 years later, UNLESS you change. Changing could mean even just faking an upbeat outgoing personality. Most popular people are just basically phonies so in a way everyone is faking it.
Anyway if you had 10 friends in high school that is pretty good. Being rude or disrespectful to people I think will actually HELP you in some ways, depending. My point is, you can actually be TOO NICE, which people also don't respect.
I just think in high school there are different categories that make you part of the loop. If you are a great athlete and the head of the student council, for example, that would give you a huge head start on the rest of the losers (which was most people). You could be a chess nerd for example, but be the most popular among that group who play chess or dungeon's and dragons or play online video games, so you could have 20 nerd friends and be popular with them, and then you would be off-limits to bullying because you have a whole giant group defending you. If you are a star athlete especially in multiple sports, you kinda are off limits to being an outcast or bullied i would guess. If you could be a star athlete and also Class president or write for the school paper or involved in some other way that makes you even more popular.
My best advice is "fake it till you make it" You can't be negative, always have a peppy fun outgoing personality, come up with a few jokes. Don't mention that you don't get along with family members, for example. Don't mention that you don't like this or that person too much. A lot of topical humor or surface humor or relationships. Everyone else's life sucks too so they don't want to be reminded of negative things. Be a complete phony if it means you being accepted. You aren't really being phony just leaving out any dark depressing thoughts or side to your personality when you are around them