Most people earning 20k or more from home, previously went out to work, and the skills and contacts they made enabled them to take the risk of going freelance/ starting their own business.
Most people earning 20k or more have to go out to work to do it, drop children off at childcare at ungodly hours, whatever.
Capital helps massively but most people still save their own capital. My OH started with nothing but 5 O-levels at 16 and has built several businesses. It took many years though and for the first decade he was working and learning in someone else's business. He still can't work from home. I'm not entrepreneurial or a risk taker so that route isn't for me. I'm middle class with an Oxbridge degree (he is working class, sink school, slept three to a bed with two of his brothers until his family got a council house) and I'll never earn what he does in my nice, relatively secure job, but even I managed to save a bit while working a few years ago and retrain for a year to take another career path to the one I was on.
What is it you want to do OP? We are still pretty lucky in this country in terms of support and opportunities, I know a lot of people who had crappy jobs after leaving school at 16 then stayed at home with young children, who have trained and gone on to have good careers after children have got a bit older for example, it is hard work and takes longer than the school-leaver route, but none have looked back.
I know a couple of people whose parents helped with deposits for a flat and one person whose parents helped her start a business, but everyone else we know has done what ever they do without capital from someone else. I only know a couple of people who are able to work from home though (graphic designer and events organiser). Both previously worked full time for companies in that field in office based jobs. The graphic designer now also works in an office as it pays much better than what he was earning freelance.