My best guess is that if you live in a 3rd world country you could possibly live comfortably just by a signature campaign, depending on which one it is though. For instance, Chipmixer which is mentioned on the thread has the capability of paying up to $300/week or $1500/month. This amount of money is way higher that Greece's minimum wage (approximately $850). Thus, if I ever entered Chipmixer, I wouldn't even have to work.
Personally, I'm satisfied on Roobet, which is paying $220/month for Sr.Members and is definitely a huge help on a monthly basis.
I think the more money you have, the more you need something better for you and your family to enjoy. Obviously we don't just live for money and work, but we have to have a way to have 3 parts out of 24 hours for rest, work and worship (if you are a believer).
I live in a province in a third world country with a minimum monthly wage of around $220, obviously $400 per month from the current signature campaign can make me think about better things like having a potential investment, buying a motorbike and so on. But so far rising inflation has made my total monthly expenses much bigger and $400 per month doesn't seem like enough for my daily needs anymore. Nearly 80% of my signature income goes to making ends meet, and the remaining 20% goes to investment assets or long-term savings. So what does it mean, even if you think that third world countries are much better than others to live in, but severe inflation has made us miserable. The minimum wage is no longer enough to make ends meet, so in the end I just think that third world countries don't always benefit you financially either because inflation is the cause of high prices.