But a much easier argument against sports betting is that it ruins the sports. Players throw. They get good at subtly cheating. The gambling apparatus latches itself to the sport, to the teams and players, the umpires and judges, the sporting organizations. With this much money on the line, it's not a matter of if but when games are thrown, cheated -- the bigger the game, the bigger the incentive. It's even easier now because of the amount of side/parlay betting that is available. It exhausts the spirit of competition.
Sports gambling is diametrically opposed to sport itself.
I'm not putting up a straw man - I'm actually in favour of it. I agree that all forms of gambling ruins lives. We would improve society if we agreed that all gambling is bad.
As a professional gambler (aka farmer) I understand I am biased, but I have a hard time squaring that society would improve if we all agreed my gambling habit is bad. Especially if that means going as far as a ban. What would people eat? If you think Mother Nature is going to give up her bookie position, you're wrong.
Gambling, in a colloquial and legal sense, generally refers to putting in money for a game of mostly luck or beyond your control in hopes of getting a payout. The less influence you have over it, the faster the payout (or loss), and the higher the chance is of you coming out at a loss, the more strongly it fits into the understood definition of gambling.
Doing anything that takes a risk isn't gambling. Bending over to tie your shoes is a risk. There's a chance you'll strain your back and be immobile for a week. But if you don't take that chance, you won't be able to work. But if you don't do it stupidly, barring the heavens simply being against you that day, you'll be fine.
Farming is the same. If you're not being careless and the heavens don't decide to destroy your crops, and particularly if you're at a point where you can call it a job, you'll be fine. Once a risk is on a long scale, like farming, it's called an investment.
Either way, you are out to lunch. Your definition is on point, but has nothing do with the discussion taking place.