I prefer using open source software where I can. The availability of the source code is one reason, while I'm not much of a coder I appreciate the fact that the code is there for review if I or someone else want to look at it. Another reason is of course that there is no cost to aquiring the software. This does not however mean I don't want to pay for software I use. I have no problem with that, and actually pay for several pieces of software, both open source and not, that does not require payment to use.
One example is the excellent RSS reader Inoreader that works perfectly well in its free version for most people. I would have had no problem using it and not paying. However I appreciate the work that Yordan Yordanov and his crew put into their product and so I gladly spend $30 for a years subscription to some extra features I don't really need.
Another example is Wikipedia. I can use Wikipedia for free and be happy with it no problem. However I see the importance of having such a resource available and I have the means available to support it so I do.