Learn English – ny proverb or idiom that conveys “the world is bound to no man”

Better late than never means exactly what it says.

it is better for someone to ​arrive or do something late than not to ​arrive or do it at all - Cambridge Dictionaries Online

Both “boom-or/and-bust and "{either} feast or famine" are pretty literal translations of your idiom, with "feast/boom" meaning "days of plenty" and "famine/bust" standing for "days of nothing."

Although "boom-or-bust" is mostly used for describing the ups and downs of whole economies and industries, I think it, and especially "famine-or-feast," would work well in your first two examples of people or governments quickly blowing through their limited budgets, resulting in them having either too many/sufficient resources or too little or no resources.

Boom-and-bust
adjective 1. characteristic of a period of economic prosperity followed by a depression.
Also, boom-or-bust

feast-or-famine
adjective 1.characterized by alternating, extremely high and low degrees of prosperity, success, volume of business, etc.: "artists who lead a feast-or-famine life."

(definitions from 'Dictionary/com' and "The Free Dictionary,' respectively)

As for your third example, I'd probably go either with any of the other good answers so far that capture the alternating feel of your proverb ('rich today, poor tomorrow'/'ebb & flow'/'ups & downs') or with the good one that, although lacking perhaps the alternation, talks of the nearly-inevitable consequences of "fools [having] money."

My own late entry for your third example (and it might also fit with the first two) would also be one that doesn't directly capture the notion of alternating fortunes:

burn a hole in/through {somebody's} pocket
If ​money is ​burning a ​hole in ​your ​pocket, you are very ​eager to ​spend it.
(from 'Cambridge Dictionaries Online')

You know, all that money just burned a hole right through his pocket. What a shame.