Taking unnecessary risk in gambling is mostly done by ignorant people, or those that are newly into the system, well it's understandable because they're ignorant of the risk management of gambling, but what baffles me is seeing experts taking unnecessary risk like betting heavily on risky odds, I consider that unwise cause no matter how rich one is you don't go wasting money all in the name of taking risks. we all know that in event where winning is a 50/50 chance one is required to bet wisely right? Then I wonder why some people would bet heavily on odds above 5 points, some would even risk all their profits to make more profits. The aim of one who wants to be successful in gambling shouldn't be to waste money in the name of taking risks, it's avoiding numerous loses and spending wisely even if you want to take risks it should be calculated risks not risking all your profits to make more profits. Stick to your limits, bet on low risk odds, take profits and don't bet all your profits one very risky odds, and most importantly bet on what you can afford to lose, these are what is expected from a gambler who wants to be successful, not taking unnecessary risks.
Emotions are hard to control and that is what makes those person to go taking unnecessary risks because of it. They are euphoric to say the least, if they win some good amount in a slot machine like for example they buy the bonus with 2.5 dollars and got an over 100 dollar win with that bet they simply become euphoric and this is the most dangerous moment which takes people to take more risks and they don't really think cold headed about the consequences, I personally have been in this example to many times and despite losing all after winning that 100 dollar with 2.5 dollar greed and euphoria got the best out of me until I lost it all, I have lost several occasions like that and I don't call it unnecessary risk rather I call it "the fight for the max win" as I chase it while losing eveyrthing.
The same can be said about people losing in sport bets example like you have provided, it is all because of the emotions which we can't control.