I've observed lonely people are either:
A: rotten people who alienate people with their behavior
B: "shy" aka self absorbed people who can't connect with people because they expect to be showered with attention instead of paying attention to others

making friends is literally the easiest thing ever: you just go up to people and find out what they're interested in and what they're like. people love talking about themselves. you'll never run out of things to say or talk about if you're not a self-absorbed, entitled prick who offer no value to others. you'll never be lonely if you offer value to others, if you don't, sorry - you deserve to be lonely.