Curiosity was often my main driving factor.

A good example was codereview.stackexchange.com/quest...

I did a code review for code in a language, I had not heard of at the time.
The example was understandable, so I gave advice. I found the language really interesting. So the next thing I did was googling elixir and started learning more about functional programming.

Most languages I learned to a level to understand what they do, how they do it and what would be a good usecase. That is perhaps far from being fluent; but I did it just for fun in my spare time.

The languages I feel mostly at home are Python and Javascript. These are my bread and butter languages to pay my bills.

I visited a mixed bag of languages.

What everybody is talking about is learning new languages.

What nobody seems to be talking about is forgetting languages when you learned languages and forgot parts of languages you once learned: I hardly remember Sinclair Basic (Dim was for arrays but I could be wrong).