>Come now, this is only an enhanced form of prisoners dilemma, where the prison guards do a side hustle helping prisoners rat each other out, in exchange for a "very small" commission. Everyone spending money on advertising is a strong Nash equilibrium, but it is not the optimal solution.

Imagine you are making your own craft beer in your basement and you are sitting on two crates of beer. You want to sell your beer but you don't tell anyone that you are selling beer because that would be advertising and according to you advertising is not an optimal solution. Even if we assume you are the only company on the planet and have no competitors, your business is still in trouble and about to make losses and close down.

>If everyone spends money on ads, a single actor choosing to not spend money on ads would (probably) see a loss. And in this case, you have a centralized actor (ad companies) spending a lot of resources telling everyone this fact.

Now we assume that you tell someone that you are selling beer which is basically what advertising is. People know that you sell beer now. They can now make a decision to buy your beer. If people like beer that's what they are going to do. If they hate beer they can still decide to not buy your beer.

Yeah, if you did not advertise then you would indeed see losses. Simply because nobody is aware of your products, meaning they are unable to buy your products. But again, no second party is involved, so you don't need a centralized actor to decide to do advertising.

>But if everyone decided to not spend money on ads, everyone (except ad companies of course) would see a win.

Since we are the only company around we are "everyone" and if we decide to not spend money on ads then we would see losses.

So now that I have proven that your hypothesis is not correct we can actually talk about the ad market in general.

Advertising is providing value for companies but the amount of value advertising can provide is not based on how many resources you spend on advertising, rather it is dependent on the size of the market. A big market with lots of consumers can make more money off of more advertising but there is a certain point beyond which you end up spending more on advertising than the market needs. On a planet with 1000 consumers and two companies the best case would be if both companies put out 500 ads. So clearly the optimum amount of advertising is not 0. However, a big company can put out 1000 ads and thereby displace its competitor's ads. It's best to have some ads but not too many.