I know this isn't the point of the article, but surely if you were a time traveller you wouldn't bet on the stock market and risk being found out or have your cash confiscated? Surely you'd research a financial instrument that has existed for a long time before your now and go back and make a modest investment in it.
You could do a number of things that are more subtle to establish ways for the investment to not be noticed, by moving the money around, etc., but I expect that your main concern would be how to fly under the radar while compounding works.
In fact, perhaps people in the time-travellers world who want to invest into their future would be chiefly concerned that time travellers in their future are coming back and dominating all the investments without ever plowing the proceeds back into their present ..
You could do a number of things that are more subtle to establish ways for the investment to not be noticed, by moving the money around, etc., but I expect that your main concern would be how to fly under the radar while compounding works.
In fact, perhaps people in the time-travellers world who want to invest into their future would be chiefly concerned that time travellers in their future are coming back and dominating all the investments without ever plowing the proceeds back into their present ..