> You need to pay for Obsidian if and only if you use it for revenue-generating, work-related activities in a company that has two or more people. Get a commercial license for each user if that's the case. Non-profit organizations do not need commercial licenses.
If it doesn't help your work or a free markdown editor provides you the same value, you have your answer.
As I use it for my job I consider it worth the 50 bucks. I still would prefer it to bee FOSS, though (and be willing to pay, anyway) - as then I knew even the software might be still around when the company behind it is gone.
A lot of utility with obsidian comes from the plugins from the community (e.g. excalidraw) and even though they might store their stuff also on your disk as text files, the utility of that eco system is gone as soon as one switches (or changes, or requires a different file format for the text files or whatnot)