It depends on how you define "successful". Lot of definitions:

1. Building a six figure revenue for solo bootstrapped founder. Work from anywhere, no team and make enough to live comfortably and travel the world.

2. Build a small company with 1-10 million in revenue. Need a small team for that. Possibly some Angel funding.

3. Build a 10+ million revenue company. Need bigger teams and possibly VC funding for quick growth.

4. Build a 100+ million revenue company. 1000s of employees. Almost definitely need VC funding.

5. Build the idea behind a company, create a product that shows tremendous traction and then SELL to another company. Profit for founders even though no real value created over a long time.

Take your pick. Each option may have a different path. I would love to be in the 4th one and still working on how to get there :)

There is no one size fits all answer to this question. What’s your definition of success? Owning your own business that pays you an above market salary and allows you to live comfortably and independently? Or do you see success as growing to being a huge global corporation? Do you want to start a company that targets consumers, small to medium businesses or large enterprises? There’s a ton of other factors that have a huge impact on a potential roadmap for success.

One bit of advice I’d offer is to know going in that software development is likely to be the least of your problems when running a software company - especially for a software engineer. Your real challenges lie in sales, marketing and customer relations. If you’re not successful at these aspects of the business, it doesn’t matter how good or bad your product or code is.

Been there. It is hard. Live like a pauper. Think B2B. Software is really about solving someone's problems. Don't be a solution in search of a problem. You need to work somewhere first, as you will see opportunities everywhere.

That's the wrong focus. You're trying to reverse engineer success. Start from the bottom. Have a problem you want to solve with software. Then gather people together to solve that problem together, create a product out of the solution, market it and sell it.

YC playbook covers most of it:http://playbook.samaltman.com/

Assuming you already have a software product, read https://kalzumeus.com article on how to sell more software/ run a software business.

http://www.ryanyosua.me/how-to-start-a-lean-startup/

Go read everything on http://stackingthebricks.com

Find a problem and solve it, to make people really need you.

Find a place to sell your solution, to make people really see you.

That's business.

You can try to apply the YC's slogan to your neighboorhood ("Make what people want").

Stay close to your customers, and always test your ideas before you scale.

Read The Four Steps to the Epiphany by @sgblank.