I have gone to at least one anime convention every year since 2012, and have attended the same one for 6 coming up on 7 years in a row, Anime Detour. I actually attended 2 in 2017, Anime Detour and A-Kon, and a whopping 4 in 2018, Anime Detour, AniMinneapolis, Anime Midwest, and Anime Expo - though for AX I was only there for the Day 0 concert. I am slated to attend 2 for sure and possibly a 3rd this year as well.
I don't cosplay, but I do attend panels and browse the artist alleys and merch halls.