Cheryl, the "best answer bandit" isn't a new phenomenon. I first encountered it about 3 years ago, when someone kept de-selecting my choice of a best answer to a question I had asked. I played the game then - kept re-selecting it - a few dozen times that day and I came back to it every day or two for a few months and always had to select it again. I finally gave up, also apologized to the person who answered for all the notifications that his answer was selected that amounted to spam because there were so many.
I've seen it several times since then, mostly either for my answers that were selected by someone else or someone else's answers that I had selected. Is it right? - no. Is there anything that can (or will) be done to prevent it? - no. In the big scheme of things, does it really matter? - no. As a result, I don't see any point to wasting time wringing my hands over it. I'd rather spend my WikiTree time productively, working on the Holocaust project, its profiles, my own family profiles, and … yes … continuing to provide information to folks who ask questions needing answers from a geek, regardless of any points or other credit that may or may not be awarded for doing so. I get two rewards from that - someone appreciates my explanations and I feel like I'm paying back (and forward) for all the genealogy help I receive here.