Enforcement is going to be pretty hard. It's the thing that Bill Gates talks about when talking about philanthropy.

If everyone in the world gets $30 - warlords in Africa, and landlords or local gangsters in other impoverished nations with weak law enforcement will easily be able to extract $25/person from their locality as 'protection money'.

Now though, if those thugs at the top end up spending that money on local businesses, they're slowly boosting their economy. But they're more likely to buy smuggled German cars, thus evading local import taxes and funneling that money back into the developed nations with zero gain for the local economy.

However, what I've stated is the worst case scenario. More likely than not, that $5 left with individuals is quite a lot in most countries and may end up boosting their economy albeit at a lower scale than what was imagined.

A lot of things need to change. Better transparent and accountable governance. Reliable and fair police/courts. Technology that can self sustain the population. (None of that patented seeds for farming).

Some level of sustainable land distribution (otherwise land lords suck all that UBI money anyway)

One could say SF is on average quite wealthy, but very broken. Even a UBI of $1000/month doesn’t do jack shit there until you solve the housing problem.

Basically people need to have good nutrition, have a roof over their head (feel secure), be autonomous and have some sort of self worth (mostly comes from doing some sort of work that creates value). All without destroying the planet (which we’re doing at an accelerated pace)

UBI doesn’t necessarily guarantee all those conditions are met.

GiveDirectly is experimenting with that kind of small-sum UBI in eastern Africa: https://www.givedirectly.org/

It would require a world government with teeth to be able to pull that off, Einstein was a famous proponent of this but even he could not make the case convincingly enough to get people to give it a try.

https://bigthink.com/paul-ratner/should-we-have-a-world-gove...

I'm no economist, but injecting that much money that fast into an economy opens a whole new can of worms with inflation and currency devaluation right?

Yes, but the net value is increased. It’s because giving $20 to a homeless person has a different effect than giving $20 to Jeff Bezos. The homeless person goes and spends it immediately, whereas Jeff Bezos’ spending habits won’t meaningfully change because of that.