They had a business model: you provide a service to your customers and your customers pay for it. As the service is awesome, customers stay. That's why for inst

They had a business model: you provide a service to your customers and your customers pay for it. As the service is awesome, customers stay. That's why for instance in Spain, it has been the de facto messaging standard for 7-8 years. People paid for it if they had to, even for the 3-year pack. They use WhatsApp for everything, it literally has replaced calls. If there are ads now this might change, as that will alienate everybody. They might consider Telegram (that'd be my bet). WhatsApp is considered standard functionality of your phone here, you'd change your mobile provider if they start playing ads in the middle of a call.