Storage/compute/etc were orders of magnitude more expensive at the time, so the fact that it was 3-4 million is uh, pretty impressive? You could host a Matrix server for your 1,000 closest friends for basically no money.
The scale issue is enabling billions of consumers. It takes time and effort and skill.
It turns out that there are relatively skilled people who are willing to give their time and resources freely relative to billions of consumers in the market.