I never feel like celebrating the releases that were shipped even solely by me. Maybe once I build something with Idris or Ada?
The industry has a major problem with burnout. If we don't slow down, and take a break, then eventually, burnout becomes inevitable. The mind gets overworked.
Some people celebrate to recharge. Others stop using a keyboard, and find something else to do.
I don't recharge around others, I find it exhausting. But after a major project ends, I do usually find myself buying the new hit PC game, or taking a hike into the mountains.
Your coworkers celebrate, so that they can feel the weight of the release lift off easier.
Something else might already be playing that role with you - and some releases will be easy for you, and several months of hellish stress for someone else.