One of the ways that some casinos can hold people back is by allow them to choose the amount of bet they would like to play. The rule is simple. If you want to bet at a lower level you can do so, but at that point, you are also going to be playing at a lower jackpot opportunity. If you want to bet more, you can do so and that means you will qualify for the higher jackpot payout. The odds of winning in any of these situations should be carefully considered, before you bet in all cases.
Nevertheless, most players will want to bet at the higher level and go for the big jackpot. The reason is actually very simple. If you do not take the time and bet at a higher level, then you will end up with a loss of opportunity to win that big jackpot.