The one delicious snack food? There are many foods I simply don’t buy often. That would be completely consumed the day of purchase, regardless of quantity. Nothing odd about food addiction - this is commonplace.
Cocktail weenies with barbecue sauce. If I had access to an infinite supply of those, I would eat them until I exploded like Mr. Creosote.
Sunflower seeds in the shell. Homemade Chex Mix. Wasabi peas.
Mini corn dogs. I could fatten up like a pig eating deep fried cornmeal and preservative laced hot dogs. Pizza rolls on the side are nice too.
Doritos Cool Ranch/Nachos. Gummi bears and variants…
Old joke
Everyone knows that Cheetos is laced with crack. You have to finish the whole bag in one sitting and need another one in a couple of hours!
Defining addictive as I crave it for days or weeks until I have it, I’ll say Cheetos, Doritos, BBQ potato chips, beef jerky and dried cuttlefish as a preference over beef jerky. Not addictive in the sense that once I have it for a few days or week (never polished off a whole regular sized bag of any of those in one sitting), I’m fine for months or years.
Right now I have open bags of everything expect Cheetos and Doritos and I alternate between them.
In Hawaii, we say “I’m 'ono* for X snack/food!”
*'ono means delicious/tasty. Not to be confused with ono (without the okina/accent mark) that means a type of fish.
So many foods. Pretzels, wasabi peas, wheat thins, goldfish, pistachios, Trenton crackers (does anyone here know them? No longer made.) Many other things. Also chocolate.
These.
And these.
And Bugles. I don’t eat them often, but they rarely last past one session. Maybe two.
White chocolate peppermint M&Ms.
The Carolina Nut Company has some amazingly flavored peanuts that are difficult to stop eating once you start. Sriracha Ranch are my favorite.
Hershey’s Chocolate Kisses. Food of the gods.
I could eat a family bag in one day, probably. They just melt on my tongue in the most scrumptious way. I wish they were calorie free.
And unwrapped.
Pistachios! 
Unshelled they are dangerously addictive, but if you buy them in the shells then you have to work to get at them.
ALL of the above, really! I could totally pig out on anything.
These days my #1 vice is sesame sticks. I have to grab a handful of them and give the rest to my husband to hide.
No way! It costs me fifty dollars a pop to get my nails done! LOL
Utz salted peanut butter pretzel thingies, lol. I am also a total sucker for Cheetos puffs and pretty much any brand of Ruffles.
I went through a kettle-style Jalapeno chip phase. I found Kettle brand to be the tastiest.
When I was on keto, pork rinds were my snack of choice-- about the only carb-free crunchy snack there is. Yes, the hot & spicy are best. Surprisingly, I found Kroger brand pork rinds to be the best. Pork rinds will have a certain percentage of discolored, very hard to crunch rinds with a funky off-flavor. Kroger brand seems to have the highest percentage of the light fluffy crunchy rinds to weird rinds.
When my kids were younger and more into Cheez-its, I found them surprisingly addictive. I would seek out the ones that were toasted a little browner than the rest. Later I discovered they came out with different flavors of Cheez-its, the most popular variant being “extra toasty”.
I just recently found the Kroger brand, and they’re as good, if not slightly better, than the Baken-ets I grew up on. Not homemade, but you don’t have to fire up the kettle & slaughter the hog, either 
If I had to pick, I like the Lay’s Kettle Cooked version, followed by Zapp’s or Bob’s.
I had never heard of chili cheese Fritos before @sitchensis’s post. Must. Not. Try.
Aw heck, who am I kidding; I’ve added them to my groc list. Bring on the polyaddiction!
Bugles OTOH. I was about 8 or 10 when they were introduced. IOW, the perfect kid age for kid food. They were then, and still are today, inedibly awful.
I am truly mystified that, like Fresca and (until recently) Tab, the product somehow hung on in the filthy rat-infested bilges of the snackfood-industrial complex’s catalog.
YMMV on Bugles there buddy. Then again, that means more for you! 