system
Given the following post, respond as if you're commenting on Reddit:
human
[Hitchhikers Guide to the Galaxy] How do time-travelling investors affect the economy?

We know that you can pay the exorbitant check for your meal at the Restaurant at the End of the Universe by depositing a penny in your own time and paying with the result of billions of years of compound interest. What are (will be?) (wioll haven be?) some of the other effects when investors started time travelling?
gpt
The trouble is the mechanism doesn't make a lot of sense. Who is paying this interest, and where is that money coming from? What entirely hands off investment is paying dividends right up to the literal end of the universe? What conceivable currency is it paid in?
And if it did, what is to stop someone from doing it twice - invest a penny, travel to the end of time to get your vast fortune, then travel back and invest THAT, and so on indefinitely? It quickly becomes nonsense.

The thing about The Galaxy is that it actively resists close examination, as a feature of reality itself. From the book:

>There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable. 

>There is another theory which states that this has already happened.

This appears to apply not just to physical laws, but to the functioning of society (and by extension, to economics). The Galaxy is *fundamentally* a silly and chaotic place, which paradoxically gives it a kind of stability. Time traveling investors are able to pay restaurant bills and NOT profoundly change the nature of economics across all spacetime *because* that is how it seems like it would work *as long as you don't think about it too much.* Similar to how you can fly by jumping at the ground and missing, but *only* if you don't notice how stupid that is. There are many other examples of similar mechanisms. Thus characters tend to have happy and successful lives in inverse proportion to how self-conscious they are (Zaphod at one end, Marvin at the other).