In fact almost all companies start off willing to accept low profit margins, or even losses when they get started
They are building a client base that will allow them to reach economies of scale or the ability to raise their prices based on reputation
Social media companies are a special case because they use the general public to provide a large part of their product (content, and access to a marketable audience)
None of these platforms can exist at break-even or better without charging users or leveraging users to charge advertisers
As for the fediverse, I’m grateful that app devs and instance hosters are doing what they do for free, but wouldn’t begrudge them one bit if they charged me or served up ads to pay for their expenses and time. Anyone that demands this must remain cost and ad free better be building their own app and hosting their own instance