Large brands continue to run ads to enforce brand loyalty and keep their image fresh. For a lot of companies, dropping advertising will lead to reduced sales.
https://www.forbes.com/sites/cmo/2024/12/18/why-cutting-adve...
However, as a new entrant to a consumer facing market, how is one supposed to drive new customers to try their product? Just being a bit better or a little cheaper isn't necessarily going to win over a lot of people if they never bother trying it due to existing brand loyalties. So you've got to do some amount of advertising to build some kind of awareness to the product and get people to try it.
That doesn't necessarily mean unskippable video advertisements or whatever, but one should try and do some kind of marketing push to get awareness of your product up other than hoping presence on some store shelves will result in enough sales fast enough to keep your company alive.