The main problem with most of the wp plugins (paid or not) is a fact that they usualy doesn’t do the things author claims they do. Iam the one who buys the plugins i use in the form of either pro version or for example patreon donation in the case of github repositories as the authors deserve (in my opinion) some sort of satisfaction appreciation.

But, there is a but. Many times i have faced one issue, needless to say it was the same issue in all cases. The changes they do to wordpress are ireversible orvl very hard to do, so paying for pro or through donations is in such cases the only option you are left with as you are basically held hostage. Prime example are plugins that add or alter user roles.

So iam all in for paying for things when i find them usefull after a trial and/or testing free version, but imho such radical things should be stated upfront, which in most cases isn't.