As you say, perspectives differ. But how much would be "enough"? The more money you get, the more you tend to spend, which generates more demand for money. People's needs frequently expand to consume the cash available to them.
Where does one draw the line? At some point (in my case, a couple of years ago in my mid-30s) you realise that while making, say, midway between 6 and 7 figures every year is a nice treadmill to be on, it's still a treadmill. Then you might be quite happy to forfeit some income in return for a slower pace of life that allows you to spend more time with your family and friends and on non-career interests instead of putting in 60-hour work weeks.
If you have two jobs - engineering AND trading - it's going to be difficult to spend much time doing anything *other* than work! I would guess (while freely admitting that I don't know anything about you) that the issue for you is how long you will continue to work two jobs and at what cost. Will you continue indefinitely? These days the opportunity cost of work is something that I think about a great deal.
Still, I must agree that $50k doesn't sound like enough to live comfortably.
Suss
on top of that, if you lose trading, it gets worse. so its better to work a couple extra years for additional buffer, or do as im trying and cut-back on work time each year.... then when trading income is greater than work income for a couple of years, its time to try trading. i think $100k in investment/passive income is enough. the one important thing is to control spending.