Okay, so let's say you do decide you can live with the worst case of doing a startup, but you're not ready to do one right now. How can you best prepare yourself to start one in the future?
To actually start a company you'll want two things, an idea and a co-founder. Now, sometimes an idea and co-founder both come to you quickly and you're off to the races. There's lots of great startup content out there about how to start a company once you're ready, but let's talk about what to do if it'll take you some time to get to that point. I'd start by encouraging you to not think of finding ideas and co-founders as two separate tasks. It's hard to think up good ideas yourself. Also, your ideas will start out being vague and fuzzy, more like a hunch or an impulse than a clearly formed idea, and you'll go through seven iterations of fleshing it out into something more tangible and concrete. Having someone to talk through that initial idea or impulse with and debate and discuss is important, and the best person to do that with is your co-founder.
I find my best ideas come to me during conversations with smart people, so I'd start by thinking about who do you know that you enjoy talking about ideas with? In college, these are often the people you'll go to when you're stuck on a hard problem, or they're the people you most enjoy working on group assignments with. At work, these are the colleagues who you find make you the most productive and help you do your best work. I'd seek these people out and start having conversations with them about ideas or technologies that you find interesting. Talk about products you use every day that you admire or are frustrated by. Talk about technologies you think are underrated today and why. Flesh your thoughts out and debate them. Spend the time between these conversations, doing your own reading and research to learn more about the topics you find interesting. If you're a curious person, this will seem natural to you anyway.
All of this primes your mind to more easily notice and think of potential startup ideas, and it helps you get to know your friends or colleagues better as potential co-founders. If you are struggling to think of people you enjoy talking about ideas with, then you probably need to change your environment and meet some new people. If you really wanna start a company one day, it's best to choose an environment where you'll be around many people who might someday be your co-founder. I think the best environment for this is working at a startup. You both get to see how a startup works from the inside, and your colleagues will be less risk averse than the average FAANG employee.
So, if you're in college, I'd recommend finding a startup to work at after graduation, or if you're at a FAANG company now, think about leaving to join a startup as an intermediate step to starting your own someday. Once you're around smart people who you enjoy talking about ideas with, I'd recommend you start experimenting with turning these ideas into side projects. At some point during these conversations, you'll eventually say something like, "Huh, like, it'd be cool if someone built X", and that's the moment to stop and think about how you could be the one to build X. Is there a simple first version you could build over a weekend? Or can you find other people who might be users and pitch them on the idea to see how they react? Keep pulling on this thread until you've come up with a plan to turn this idea into something real, however small it is. Right now, you're not trying to launch the next unicorn. You're just getting used to the experience of turning ideas into reality and experiencing the thrill of launching something.
To turn your idea into something real, you'll need the skills to actually build them. If you're not a programmer, then either you'll need to learn how to program or find a co-founder who is a programmer. My advice, speaking from experience as someone who started his first startup without being able to code, is start learning to code. You only need to learn enough to build a version one of your ideas.
Once you're around smart people, and you're working on some side projects, how do you know when it's time to take the leap and quit your job to start a company? While it'd be great if one of your side projects started getting explosive traction and made the decision easy for you, you can't rely on that happening if you're serious about starting a company someday. Even if you launch your side projects and get some early users, the feedback you get will be mixed. It's not uncommon for the early users of any product to span the spectrum of being delighted, appalled, and indifferent towards a product.
To judge how promising your side project is as a startup idea, I'd use some advice from my Y Combinator partner, Paul Buchheit. He says that it's better to make a product that a few people really love than one a lot of people are indifferent towards. If your side project elicits a deep reaction from someone, the kind where they can legitimately say that doing something very differently as a result of your product existing, then you may be onto something. A single passionate user of a crude prototype that was hacked together on a weekend means so much more than a million signups on a waitlist for something that doesn't exist yet.
My main advice to you would be to think less about how well your side projects are going, and think more about how much you're enjoying the process of thinking up ideas and turning them into something real. Are you learning new things and finding yourself energized? Contrast this feeling with your day job. If you find your job is draining, but you have energy to work on your side projects on evenings and weekends, that's a sign it may be time to quit and work on your own ideas. Pay particular attention to how much you enjoy working with your side project collaborators. If you enjoy working with them and you both want to be startup founders, recognize how rare that is. Having a great co-founder who wants to do a startup is a fantastic reason to quit and start one.