Not the parent poster, but have done this all my live. In The Netherlands people generally stop biking for sport in the winter, yet continue biking to work, which shows that your observation that it looses its fun is largely shared. It’s just that the benefits keep outweighing the drawbacks: it’s cheap, fast (at least in congested cities), sustainable, and good for your health.

Then again, it’s much easier to keep doing something when everybody else is doing it, so if you’re in an area where cyclists are a minority I imagine it’s more of a challenge to convince yourself. The advantages do still apply so I’m sending virtual encouragement!