That might be one reason why some warned against using it, but I definitely had teachers in middle school and high school that explicitly said not to use it because it could be changed by anyone including people who could be wrong or lying.

In a sense it is a monopoly, just a very narrow one. The first step to identifying a monopoly is identifying the relevant market, and that is quite hard to do, actually.

They also want to be able to support their families by making money through the Obsidian application, which could be more difficult in an open source environment.

This is the only one that seems really legit to me. That and the other commenter that said open source is more work, which is probably true, and if you’re not getting benefit it could be a net loss.

There are lots of good ideas out there, I’ll just add some that are pretty niche:

1. Anything that is legal to do for free is also legal to do for money.
2. All laws must have a justification for them written into something like a preamble. If the justification turns out not to be true, winning something like a basic law suit against the law is all that is needed to have the law struck down. No need to wait for legislators to pass a repeal bill or for a very specific case to make its way to a supreme court.