Yes, but there are lots of platforms used by niche groups, and a few platforms used by lots of people. Scaling up to Whatsapp levels is a money-intensive process. And then you start to need sales, marketing, customer support, sales support, legal, expertise, developers, QA engineers, sysops, scrum-masters, project managers, finance and accounting, payroll, HR, technical writers, training the usual layers of management for all that, and then all the hardware and hosting and capex and opex, from pay for cloud or datacentre hosting to the PC on someone's desk, not to mention the costs of the data, licensing, etc. There's more, I'm sure, but I'm still on my first cup of coffee.
These days, I'm responsible for a very niche platform, and that eats double-figure millions in direct costs without accounting for much of the above.