This is a very common question, and the short answer is - work hard and don't listen to your naysayers nor your lizard brain.
Starting a business doesn't require any capital, but often times many entrepreneurs aren't skillful enough to couple swagger + brute determination + insight. You have to know that it isn't about what you have, what you don't have or who you know but about how willing you are to pivot your efforts, try the same thing 3 times 3 different ways before saying that strategy didn't work, how good are you at negotiating distractions and negativity like self doubt.

I have helped several companies launch out of pure ideas and coached entrepreneurs to hustle their way to obtaining an MVP or minimal business product inventory to generate sales, in some cases you can sell before you even having a product. It all depends on the person, how likable that person is and whether or not the entrepreneur can be laser focused.

When you don't have money then you need time and clarity (that's why communities like this one here are so vital)
When you don't have time or money, then you need swagger and dedication to be everywhere, meet as many strategic potential partners as possible, learn from them, build relationships and get liked - is not about you who know but who you know and if they like you.

My name is Humberto Valle, I'm the co-founder of a global digital marketing agency (www.Unthink.me) and I have been working with startups for about 10 years and launched and exited 2 successful (no big deal though) startups myself. Best of luck, if you have any specific questions follow up and send me a message.