They can still infiltrate them by buying their way into the admin/s pokets since maintaining servers is expensive.
Yeah anyone who thinks activityPub is immune to monetization is delusional.
It honestly doesn’t seem that expensive based on others talking about their hosting costs. The bigger instance will be more expensive but they would also have a lot more people who can easily handle the cost without needing external funds. That said some instance will go that way not for the server cost but for simply money in their pocket at which point you can just switch to another instance.
It gets more expensive if you strart a successful meme community with lots of data. Some big Mastodon servers already store gigabytes per hour. Even with Cloudflare the expenses can soon get pretty high.
But yes, everything else with Lemmy is just a few euros a month.
I still don’t understand why they aren’t just utilizing imgur and that catbox hosting service exclusively. Plenty of image/gif hosting options.