This is ironically is the biggest problem with the fediverse in my opinion, eveything is connected and interoperable in some way but also not fully. It’s confusing and probably puts a lot of people off
Every single rapist and murderer was found to have dihydrogen monoxide inside their body at the time they committed their crimes, and your friends and family may be using it recreationally without you knowing
True, but the amount of instances will probably scale too. You can have premium instances that cost a monthly fee, ones that solicit donations, maybe ones that run ads. But you'll also always have the passion project instances being ran for a specific community out of the kindness of someone's heart.
Everything needs to generate some sort of value - I imagine a lemmy instance would generate value for you in the form of learning, or maybe the sense of accomplishment from maintaining a community. That differs from how centralised social media generates value in the form of data or money which is usually at odds with the userbase.