First, I'm going to assume for my example this is net post-tax income (so the base capital amount would need to change a bit).
In the US or any country with similar expenses:
I would say 120k. This covers rent in even the most expensive cities with enough to eat out, travel overseas modestly (once a month for two weeks if desired), and have enough extra income to make sizable investments to grow my bank account and/or splurge on a serious luxury item/event each year. Or if you wanted to be a brave soul, you could use the extra money to fund the expenses necessary to have a family in a modern country.
1. NYC/expensive city rental expenses: $3.5k month = $42,000/year
2. Food/Eating out: = $1000/month = $12,000/year
3. Travel/2 weeks per month = 2k month = 24,000/year
4. Health Insurance/basic living essentials = 8,000/year
So, $42,000 + $12,000 + $24,000 + $8,000 = $86,000/year
$120,000 - $86,000 = $34,000 <----- Leftover do whatever the fuck ever money.
Now, keep in mind that this is worse case scenario. I'm living in a very expensive city, eating out all the time, and traveling spending 2k a month every month. I could just as easily live in a cheaper part of a modern country, eat out less, and travel less and bank way more money. But even in the worse case, I still have 34k leftover to do whatever the fuck I feel like it; which most of would probably go into investments to help the base fund grow to combat any inflation.
If needed, I can live in most parts of the US on about 20-25k/year pretty comfortably (all basics covered) but its a very spartan lifestyle with almost no traveling or way to grow net worth. The aforementioned 120k allows one to live VERY good in the most expensive locations, travel, AND still grow net worth without working.
2nd/3rd world:
Probably 60k or whatever is necessary to replicate the 120k/USA lifestyle mentioned above. I have no experience living in the 2nd/3rd world but having read a ton about peoples travel experiences on RVF, 5k/month apparently goes a long way in living very well in these countries and in many respects, one often lives better on 60k in these countries vs 120k in the US/modern countries.
Ideally, I have 120k/year to work with in a 2nd/3rd world country and can live like a king.
For me at least, anything more than 120k/60k really doesn't provide much extra value. A slightly bigger house? A slightly better car? Who cares.
You have to get near 50 million and up net worths to see any really significant changes: Running for big political offices without outside money, private jets, yachts, massive estates, ultra first class everything across the board. I'm talking the amount of money where you go from being just a very well off upper class guy to a titan. But getting to that level usually involves massive sacrifices, connections, a good starting position, and lots of luck. If it happens, that's great. But I'm not going to waste years or decades chasing what is largely a phantom.
I much rather be 35 living on 60k/year (or whatever 120k USA equivalent is) surrounded by hot latinas and maybe even starting a family somewhere in South America or doing whatever I want pursuing a purpose vs being 55 but having 3.5 million/year but having lost a lot of younger years to simply chasing money.
The following video is very relevant in light of what Sigma said about how retirement/having a lot of money can feel boring and meaningless. It's President Nixon post-resignation talking about life and living one with a purpose. I've posted it before. It's real talk and I think is something everyone reading this thread should watch and keep in mind when pursing passive income goals. In that, if and when you make it to your goal of not needing to work anymore: what's next? What will the next fight be?
Again, it's something I feel every man here should always be thinking about prior to reaching their passive income objectives.
