Betting can come in any form, as long as its part of what constitutes an invent, a program or a game to bet on, people will no mind on the procedures or dip dipper than the main subject in consideration for them to be able to bet, as the presidential race is getting closer and tougher, some will prefer making their bets on this, because they wanted to ascertain their own personal convictions towards the condition ahead on bet.
You are right for those who play for fun only. But who plays to make money a large investor can't play for those events which can be manipulated. As the site can manipulate even large investors can manipulate the result. As a result, the gambler might be a loser for the manipulation.
Choosing from the selected site to earn money is much more uncertain in terms of expected profit for a gambler which is a guarantee of more profit for developers. Most of the gambling sites manipulate which makes the experienced gamblers lose and I think the developers set the gambling algorithm in such a way that they can read the gamblers preconceptions and accordingly a gambler loses. Not only do they force gamblers to lose but in some cases they allow gamblers to win which attracts them to gambling.