Risk is the downside of chance. As a final example, here's one from the upside, gambling. Well, we say that, but of course the odds are that you will lose. Though if the UK lottery jackpot reaches more than £14m, it is possible to win for sure by buying tickets for all combinations of numbers, of which there are 14 million. Although tricky to organise, it would win all the subsidiary prizes as well, so you could make a tidy profit. Well, perhaps.
Because what if someone else wins too, and the jackpot is shared? You might be ruined. So even a sure thing can be risky.
So let's say you fancied a £100,000 Maserati, but sadly had only a pound. And let's assume you are a cool, rational customer who wants the best odds (admittedly this is an implausible combination of characteristics). If you buy a single lottery ticket, and if your choice of six numbers matches five winning balls plus the bonus number (a seventh ball drawn), then this generally wins about £100,000 and has a probability 1 in 2,330,636.
Or you could go for an accumulator on the horses: pick a meeting with six races, and in each race choose a horse at medium odds of around 6-1. An accumulator, in which the winnings of each race are passed to the next horse, will give you 7×7×7×7×7×7 = £117,000 if they all win. Given a bookmaker's margin of, say, 12% each bet, the true odds may be around 1 in 230,000 – 10 times as good as the lottery
If you can find a casino that will let you bet just £1, place it on your lucky number between 1 and 36. When it wins, leave the £36 there or move it to another number. When that comes up, do the same again. Win and you will have £46,656. Move it to red, win and you will have £93,312, almost enough for your Maserati. The chances of this on a European roulette wheel with one zero are 1/37×1/37×1/37×18/37 = 1 in 104,120, twice as good as the horses.