caffeine is legal and heavily lobbied, so the supp companies absolutely love getting you hooked on it and depending on it
the truth is using stims preworkout are counter productive. there is no actual evidence, only junk science, that proves they help build muscle (and anyone who thinks this is flat out retarded). it also does not boost your workouts and endurance. they actually drag it down. you want your resting HR to be as low as possible to have the most energy and endurance, so why spike it by taking something? makes no sense.. there is a reason runners and swimmers don't sit there before the race drinking coffee lol, cause it does a lot of harm and if you don't believe me get a heart rate monitor and see the difference between being on stims and not during a workout.
the reality is you are addicted to this shit so now you gotta take it just to function.
don't use ANYTHING preworkout that is a stimulant.
and if your goals are greater endurance get cardarine