The third way is to add sweat equity and build a business slowly around your normal 9-5.

There is just as much downside to this route, it’s also risky, you take time away from hobbies and relationships, and even if you’re successful there’s a period where you will basically just have two full time jobs.

That said, I did it this way, and I know a lot of others that have, and I was able to see it through. Timeline:

2012 - hired as a senior engineer at a tech company

2014 - founded my startup Cronitor with a friend. Launched after 3 months of weekend hacking.

2015 - promoted to eng manager in my day job

2017 - promoted to senior manager

2019 - promoted to director

2020 - left job as director

2023 - still working on Cronitor, still growing, we have grown roughly 5x since I left my day job.