Loner is someone who very well can be extremely extrovert.
Someone who can have a lot of so called friends, out of which 90% doesn't have anything better to do except gamble, drink, and waste time this wonderful Universe presented us with. That loner despises herd mentality which is basis of contemporary world and its everyday happenings.
That loner, high intelligent as he is, and realizing that man is measure of all things, can downgrade himself to the level of fools and idiots, but he feels lousy afterward, because after all he is above good and bad and all subjective truths, especially spoken by his superficial and shallow-minded so called "friends".
He has real friends, but they have life besides him, like he does. He has a lot of them, yet they have a lot of their obligations and enjoyments instead of plain coffee drinking, conspicuous alcohol consumption, card, slot and roulette playing, gossiping, and all of the vices, his so called "friends" are engrossed in every day, waiting salvation to come, something to change.
These pseudo-friends are not culprits for his decision to become loner, voluntary outcast and social misfit, because they just make statistical majority of population, they are that background noise that mars music and fills Universe. They are here for artisan to create, for flower to flourish. He has arisen amongst them like rose in dirt, like massive supernova amid plain sun-like stars, "existenz" that does not need the Other to approve of it, just because He is.
On some subconscious, deeply hidden level, he feels grateful for that immensely funny moments filled with their infinite stupidity and absurdity, senseless discourses and dilemmas about trivial and banal things, that show real nature of Universe itself, presenting him with his freedom. His freedom he deserved watching, perceiving and finally understanding this absurdity and nonsenseless. His innocence he takes for granted, because he didn't ask to be born, yet he doesn't want to die.
Anyway, these mundane enjoyment, our loner left behind, preferring company of his real friends, and "same-level" friends, ones filled with intelligence, reason, advanced morals, leaders not wanted to lead, yet despising more those who follows, wise, silent sages, loners themselves, loving company of the likes, true übermansch.
Do not sexually underestimate him, diminish his masculinity, because he likes sex, he has sex. More options at sex than most guys he knows. He nails better chicks then they. Yet whether he finds them shallow or unattractive, he leaves them eventually, not being afraid of being alone, not wanting to pay outrageous price for sex: hours of prologue and epilogue that precedes and follows that same coitus, hours filled with utter stupidity and horrifying emptiness. He can live in company of Marcus Aurelius, Epicurus, Epictetus, Diogenes, Socrates, Seneca. History is abundant of his colleagues in the quest of solving riddle of life. Even modern thinkers are his friend, among which the dearest to his heart is the one who said: "Very tall tree is sentenced to live and grow all alone". This dearest friend is Friedrich Nietzsche.
That type of loner, very often is me. Sometimes I succumb to my animal instincts and socialize with "downers" and human animals, non authentic beings, just for the sake of forgetting myself, losing myself in anesthetic laughter. Here, I do not think of my dog, with whom I enjoy running through woods every day I love dearly.