Make sure to actually understand how those “non-profit” websites and services are functioning.
Generally speaking if you aren't the customer then you are the product. Individual Lemmy and Mastadon instances are getting around this for now because they are small enough that their operational costs can be covered by the ideologically motivated instance admins and users. If Lemmy or Mastadon ever gains wide popularity this will change.
No they won't, Reddit killed Internet Forums, Threads has over 200 million active monthly users, and BlueSky already has double the number of users of Mastadon and is adding 10 new ones PER SECOND . Mastadon will be entirely irrelevant by the end of Q1 2025.
What we're watching right now is the exact same fight that the chat platforms had back in the early 2000s. AOL chat vs IRC vs Yahoo Chat vs Microsoft Messenger. That was temporarily addressed by using multi-service clients like Trillian...and then Facebook rolled in and squashed them all. BTW there are several multi-platform clients out there right now that will allow you to interact with Xitter, Threads, BlueSky, and Mastadon simultaneously just like the Trillian of old.
I've been around the Internet since the BBS days and I can't think of a single time where a de-centralized platform has out competed a centralized platform with "normal" users.