missing some context... when did kazoo started collecting hats?
Few strips ago. Kaz wanted another 'leaf' to play with so he lifted Wanderer's hat. Wanderer doesn't have an ahoge, though, so he put on his hat and walked away. Wanderer called Yanfei to sue him but Kazoo just took Yanfei's hat...and presumably continued doing so with Hutao and QiQi before getting Ayaka's.
Edit: it appears this piece inspired quitefewmemes in the memepact subreddit.