Sugar and caffeine, it's addictive twice over.

Although that also describes another beverage, coffee. The difference between the coffee and soft drink industries is interesting though. Two massive corporations dominate almost the entire soft drink industry, with a handful of minor providers (notably Keurig Dr Pepper) and a long tail of much smaller 'boutique', novelty, or regional brands. Comparatively, no coffee company controls as much of the industry as either the Coca Cola Company or PepsiCo do.

(Also, PepsiCo in particular owns a ton of other non-beverage brands. Their subsidiary Frito-Lay produces the brands Lay's, Cheetos, Doritos, etc. PepsiCo is huge for American consumers. To your point though, snack food isn't much better than sugar water.)

I'm more worried about the huge supporting portion of the economy that is advertising. Seems to have much more harmful effects on everything around us, including but not limited to making people consume more terrible products such as soda than they otherwise would.

Pop isn’t a terrible product. The issue, like anything, is overuse.

You can make the same argument for anything, from butter to guns to video games to literally anything that plugs into the wall and consumes electricity.

Use anything beyond reason and it becomes destructive.