I was never a fan of the drink itself, but I remember when Mountain Dew ruled the '90s with commercials like this:
Now you don't really hear much from "The Dew." (Maybe that's also because people started called Donald Trump "The Donald")
What I think has happened is - through no fault of M.D. itself - the demographic for the soda vanished.
Think about it.
Mountain Dew was the X-treme soda of the 1990s. Commercials featuring skydivers and BASE jumpers told consumers that Dew was it for energy-boosting beverages, and consumers listened intently and acted on it. Anytime a group of kids were staying up late playing video games or whatever, you could be sure a pack of Mountain Dew would accompany them. Nobody could deny the impact Mountain Dew's high-sugar/caffeine content had on people, and nobody could compete with it either.
Then came along drinks like Rockstar, Monster, and Red Bull, with enough caffeine to make a Starbuck's patron puke.
According to energyfiend.com, the Mountain Dew with highest caffeine to product ratio (mg/oz) is Mountain Dew Game Fuel with 6 mg/oz. Most of the other Mountain Dew products are around 4.5 mg/oz.
Rockstar has a variety of products, with the highest being 80 mg/oz (Rockstar Energy Shot) and the lowest listed being about 10 mg/oz (Rockstar Juiced). Most of Rockstar's drinks are listed at about 15 mg/oz.
Monster also has a drink with 80 mg/oz (Monster Hitman Sniper), but most of its other products are at about 10 mg/oz. Red Bull is listed at 9.64, but its "energy shot" product has 40 mg/oz. So Red Bull and these other drinks may give you wings, but it also has a chance of giving you nervousness, irritability, anxiety, tremulousness, insomnia, and heart palpitations if you drink it, or any of these other drinks, too much.
Outside of incredibly ironic names, these drinks carry with them another kind of danger. I am in high schools all the time, and I see way more kids with these kinds of "energy drinks" in their hands than how many used to carry Mountain Dew when I was their age. So my fear is that, outside of the aforementioned side effects (which should instill enough fear by themselves), this kind of erratic behavior will increase among the youth as well as adults:
Long story short, many kids all across America are drinking these kinds of sodas at an alarming rate, and when you consider a can of it carries more than twice the levels of caffeine than a regular cup of coffee, the health consequences could be horrifying.
These drinks put the kibosh on Mountain Dew's clever marketing campaign, imagine what they could do to you and your family.