4% withdrawal rate is a conservative figure often used to live “forever” from a portfolio (use 3% if you want to be more conservative, 5-6% for more risk friendly).

To get $30k a year, that’s a starting portfolio of $750k. [0]

If you’re making $140k a year and living frugally, you can amass $750k in less than 10 years, perhaps even 5-7 if you are really frugal + lucky with the market.

It’s within reach of most software engineers, to be honest - but of course many people prefer the regular ski trips, new Tesla every few years, and so on. But if your dream is to work on your own stuff free of bosses/corporate politics/etc, it might be worth doing.

$30k a year won’t be much of a living in the Bay Area or New York, but for a single dependent person it’s quite alright; and in many mid sized European cities with socialized healthcare/university/etc, it’ll even let you raise a kid or two without having to sacrifice much.

[0]: http://www.firecalc.com/ gives us an 80% chance of success for a $750k portfolio on $30k withdrawal a year over 50 years.

If you’re new to this and want to delve further, check out https://www.reddit.com/r/financialindependence/