Oh, I completely agree. What I mean is that a not for profit can still live in the commercial world of it wants.
Not for profits still need stuff. Like offices or servers or staff. How the funding comes about without compromising the mission is the question.
Look at cancer charities fund raising. Look at Wikipedia. Look at Firefox.
The funding model doesn't have to be the same for every instance. Some could be just volunteer funded or donated by the admins as a cost of their hobby.
However, the broader community will not tolerate a social media space that is not professionally run with uptime and lack of errors and downtime. The only way the commercial ones die is if the free ones are better. Look at piracy. It's not a cost problem in music versus movies versus games, it's a service problem.