"Will competition get you killed on the street?"
Short answer:
No. And it likely will help.
A long winded metaphor:
I grew up on a commercial sheep operation, that also had a flock of show quality Dorsets. The commercial flock was the moneymakers, the high-production/low-cost animals that where generally raised VERY differently from the show flock. The show flock was a group of hay and grain burners. The "show" side of the sheep industry has long since become so detached from actual productivity and efficiency, that they are completely different things that have absolutely nothing in common except for species.
My father was a sheep judge at the Adams county fair some years ago, he was essentially ranking a group of about 20 ewelambs (1-2 years old). The group of animals was fairly typical except for one smaller somewhat scraggly ewe lamb that the spectators and showmen assumed would end up in the bottom of the class. My father noticed however that, unlike the rest of the animals in the class, this animal was lactating. This meant it had produced at least one lamb that year, and, given the time of year, the (at least one) lamb had made it to weaning age. This meant that this animal had been more productive, more profitable, than any of the other supposedly higher quality animals in the show ring. My father, acting on principle, knowing full well that there would be backlash, awarded Grand Champion Ewe Lamb to the scraggly/undersized lactating ewe. My father, who was in charge of the largest federally owned flock of research ovines in the United States for +30 years, who held a masters in Animal Science and Ruminant Nutrition, who likely is the single greatest resource of knowledge and skill in the sheep industry, received a variety of personal and professional attacks, and has not been asked to judge anywhere ever since. Let that backlash stand as the greatest direct example of the rift between real world commercial production and competition, that I have ever seen.
My thoughts
I do NOT believe competition is the end-all of tactical firearms training. I do think there is alot of very good competition, that does have the benefit of putting mental (and sometimes physical) stress on the shooter, as well as putting "man vs man" in the form of times and scores. Some competitions, the ones I prefer to invest my limited time and funds in, actually do a very good job of "shoring the gap" between competition and real world, by deducting points for failing to utilize cover, etc.
I have seen many competitions, most recently F-class (or as I call it, "prone benchrest"), that I do not believe hold enough training value to be worth my time and money. I watched a 3 gun competition where, instead of taking cover behind a barrel and utilizing it for support, the shooter stands in the open and engage a series of targets. The common theme is that the only objectively measurable performance values are speed and accuracy, but I would hope that most would agree, there is much much much more to the real world.
The most tangible difference is usually seen in equipment, giant F-class bipods that no one would ever want to lug around "in the real world," similar examples can be seen in most other types of competition.
Conclusion:
There is a critical balance between competition and real world that must be carefully watched. It is up to the individual to decide what is worth their time and money, as there is no magical dividing line. Also remember that speed and accuracy, while crucial, are far from the only attributes that lead to winning a "Firefight." But even with something as "non-tactical" as benchrest, shooting for competition is inevitably better than not shooting at all.