I have been attending American kickboxing classes for about a year and a half. I would like to know if practicing American kickboxing for street fight is useful or useless? Can you as a American kickboxer be confident in a street fight? I know one club that offers, Krav maga, MMA, Submission wrestling and Muay Thai. Should I stop practicing American kickboxing if it's not useful?
Depends on the club more than the style. If it's full contact and you get a lot of sparring you will have a far better advantage on the street than the average joe.
I would not call it anyhtign more than a combatsport and think you shoudl do self defence oreintated things if you wanted self defence, but its better than nothing. Still coosts fitness, gets fighting experience and can be fun.
Combat sports beat non-sport at SD most of the time simply because they have pressure inherent in the training
It can depend very much on how the club trains. On paper, most American kickboxing clubs have a solid level of striking training that will give you a good advantage.