[abdullahkhalids]

Think of Discord. Anyone can create and participate in a discord server. There are no ads. People with money pay for the premium features and perks and that is how the company makes money [1].

Not every product category is amenable to such business models but many are.

[1] To be fair, Discord likely sells user data to advertisers to make additional money.

[prododev]

Discord has ads, though they are relatively rare and not embedded in chat. They are called "Quests" and you can disable them in the settings.