You take the money you would've spent on ads and instead offer a lower price than the current leader to make up for the buyer's uncertainty toward your product. This lets a search algorithm organically decide that you are among the top (risk-neutral) value contenders. Once that uncertainty disappears, you will have a higher value product and can therefore command a higher price.

Put another way, the buyer uncertainty about your product actually, concretely makes your product worse. They don't know whether your thing will fail. The don't know whether you will go out of business if they need support. All else equal, either your product is not the best product, or you need to offer a lower price. Ads are a way to instead just pay someone to straight up lie (i.e. defraud) and say it's recommended when it's not.