Wanting to be popular is an innate human desire. You don't know why you want popularity or how to get it but it hurts when you're unpopular. I have some theories and experiences with popularity which I'd like to share with anyone interested.
In my opinion, many of our behaviors are controlled by survival urges. In the case of popularity, it would bring about the mutual growth and protection of an individual and his or her tribe. By being popular, you adhere to the tribe's standards; you can count on the tribe to protect you and the tribe can count on you to protect it.
Tribes have long disappeared from the social horizon but the urge to form tribes remains so people form cliques instead. Everything that applies to a tribe applies to a clique as well, meaning it's a group where an understanding is shared and anyone trying to infringe on the clique is swiftly dealt with to promote the growth and protection of each member and the whole.
EtymOnline.com defines the word "popular" as stemming from the Latin phrase meaning "suited for ordinary people". This already tells you that, if there's anything in you that's not suited for ordinary people, it will prevent you from being popular. The clique will identify the unsuitable part of you and unanimously vote to push you away. In short, being popular means having the most common personality traits, acting like everyone else and liking what everyone else is already liking. You are not meant to upset the status quo, the current state of things.
If you want popularity, you have to whittle down the expression of all your personality traits and skills so they are as milquetoast as possible until an opportunity presents itself for you to express them. You are not meant to stand out from the background, except in a couple of commonly accepted passive categories, such as grades or height.
If you're feeling unpopular and don't have the patience to stand in the background, you'll likely try to double down on attempts to fit in and get with the popular clique by mimicking its members in appearance and behavior. Sadly, that never works. If you persist, the clique will easily turn against you because they all think the same and their thoughts would basically be "this person is upsetting our milquetoast environment".
What happens next is fascinating and basically comes down to covert sabotage. The clique might offer the unpopular person some hazing rituals that are designed to hurt, unmask and humiliate rather than create a sense of common belonging. In rare cases, the clique might actually conspire to beat up the person or leave it stranded somewhere. You just can't fit in by forcing yourself in. Instead, what you should do is minimize energy expenditure, stay in the background and focus on creating some worthwhile environment.
You are not meant to put any energy towards becoming popular. You should do what you normally do until you find yourself in the right place at the right time. You will know it because there will be a certain buzz in the air without you having to use any drugs to feel it. So, patiently wait in the background and observe what's going on until you get the chance to excel in that one weird personality trait or skill you have and catch the group's attention. When the group assigns you a nickname, you're in.
My advice is to observe the clique from a safe distance and wait for the energy level to become rambunctious. You should feel like a hyena that's watching the lions eat and scavenge any tidbits of meat you can when the lions aren't looking. The lions sense your presence but are too occupied with eating to chase you away unless you become too much of a nuisance or a threat. So, chill in the background, get whatever you can, don't be a nuisance or a threat and find people you can relate to.
Anything that's not conforming to the popular opinion gets pushed to the background. That's where the feeling of loneliness kicks in. In my opinion and experience, the loneliness actually comes from some other life circumstances, especially weak family presence, so the unpopular person wants to experience a sense of belonging and family protection in the clique. When the desperation becomes palpable, the clique reacts and pushes the unpopular person away, and as the cycle repeats, the person sinks lower and lower.
As you exist in the background and meet people you can relate to, you will find yourself bonding around some common thing. If you build on that common thing, you'll eventually make a subculture, which is typically about a niche interest like comics or drawing. As you do so, you will essentially make your own tribe, which can be as few as 3 people.
The natural question is: "How do I become popular with girls/guys?" I can only speak for guys wanting to attract girls – you need to actually avoid them and build positive guy relationships. The thing is that girls show an in-group preference and will most often defend their cliques with fang and claw from boys but boys won't do the same to girls. Boys will typically want to embrace and protect the girl, who will feel like in daddy's arms. Just be careful not to get your group Yoko Ono'd by the little vixen.
Within the guy group, you should joke freely, have fun and support one another. If a girl approaches, she most likely wants a gangbang, which is for many of them a secret sex fantasy. If that's the case, get her through the gauntlet, kick her out of the group and move on. Keep in mind, this is what frat boys already do and it can get them in trouble if things get out of hand. For more info on what can happen, research "mattress girl" and "Sabrina Erdely Rolling Stone". So, discretion is paramount or prepare yourself for accusations of toxic masculinity etc. that can go worldwide by the media churning out vile clickbait.
If you were to ask popular people how they did it, they'd probably shrug their shoulders and say they don't even notice the popularity; for them, it's something that simply happened without conscious effort. I think that's the secret of becoming popular. You should carry on, doing what you normally do and wait for your moment to grab the group's attention.
Loneliness still sucks but in 2020 it sucks way less than ever before. You should engage with people on your own terms and try to be in an environment that will protect you and that you will want to protect. Save your energy, observe and don't double down. As you relax and observe, you will develop your own sense of worth that isn't derived from the group and become popular without even knowing how or why it happened. Afterwards, when someone asks how you did it, you will most likely say: "I didn't even notice it, it just happened".