I’m surprised by gaslight as Most Likely to Succeed since, as Dave notes, it’s already succeeded. OED cites it from 1969 and I remember it as certainly current in the UK by the mid to late 70s. I wasn’t aware of any particular resurgence of use over the last year but I bow to the ADS.
That was my first thought too, but then I noticed the category was “Most Useful / Most Likely to Succeed.” I wasn’t at the meeting to hear the deliberations, but as I mentioned, I’ll bet that it came in under the “Most Useful” flag. There has definitely been a resurgence of the term. I’m hearing it all over the place, where only a couple of years ago it was a rare word. (Not just diegogarcity, as I was quite familiar with it before.)
I also think there may be a shift in meaning going on. My impression, and it’s just a subjective impression, is that the word is being used in the sense of “convince someone what they thought had happened/is happening isn’t,” with a de-emphasis on doubting one’s sanity.