at todays conversion rate one lottery was about 4 cents, and price money was about 20 cents. these lotteries were preprinted with the numbers and available only at lottery vendors across the town, one vendor would have about 20-100 of the same number, so if he believed he would win, he will buy one number each for the predicted number and one for one random number and then buy those 2 in volume of hundreds across the town. it was pretty addictive
So let's see... You say he had a 70% chance of winning, so if the prize money was 20 cents, each ticket had an expected value of 0.720=14 cents but a cost of 4 cents so a net of 10 cents. I'm not sure what you mean by '20-100 of the same number' - he could only buy 20-100 from each vendor? Let's say he can buy 100 at a vendor (if they're the same number and so the entire batch will win or lose, then that renders the expected net value a little worse a fit but whatever) , that's 10 cents 100 or 10 dollars.
In the US, minimum wage tends to come out around $7, so if he can hit one vendor per hour then I suppose he'd be showing a reasonable profit. But you also need to take into account wear and tear on vehicles, risk of accidents, planning your life around the lottery... I suspect with those included, it'd still be net-positive but not really that great a use of time and effort. Personally, I'd be doing it more for a fun write-up than to make money.
