I've been thinking of retiring from algorithm contests for a while, having failed to qualify for any on-sites in 2017 or 2018 (I'm excluding DCJ from algorithm contests). This is definitely a young person's game and I can feel I'm not as sharp as I used to be. I still love problem solving, but when I'm under time pressure and just can't see the solution and know my rating is going to crash, I get so stressed and frustrated that I don't enjoy it any more.
Now that both my Topcoder and Codeforces ratings are back over 3000 I've decided to retire from rated contests so that I'll go out on a high. I will most likely continue to do unrated contests where if I have a bad day I can just walk away instead of stressing myself out. I might also get more involved in testing contests.