Is it possible for someone to completely stop learning due to a lack of interest in knowledge?

I'm not sure what inspired you to ask this question, but I am guessing that you are either a senior citizen, or a thirty something who is growing up. It is only my opinion but, as a senior, I have lost knowledge of things I used to be interested in and what I have studied. I suppose if I revisited those areas I would more quickly learn again as opposed to learning it for the 1st time. If you are a younger person, the experience can be similar in that you've given up the old ways of thinking and thereby forgetting what once was more important. Either way, if you don't use it for your job or profession, you lose it…

I hope that was helpful.