1. I had a consistent editing experience for those 10+ years, and expect to have it for decades to come - vim is everywhere, and it works the same everywhere (well at least if you stay away from things that may not be time-proof, like plugins that rely on Python support). It gives me peace of mind - it's a stable factor amongst things that tend to change every 6 months, usually for no good reason.
2. I have a comfortable editing experience, one that is so ingrained that it has become transparent (meaning, I don't notice it any more, like a good pair of shoes that are so comfortable you don't notice wearing them). When I use Visual Studio on a machine with no Viemu installed, there is this continuous nagging feeling that the editing is so sub-optimal. Again I don't know if the time I spend learning vim is objectively justified when compared to the annoyances of the editing in 'plain' editors, but it certainly made for a great quality of life improvement.
I got to go everywhere I wanted to go with my old Citroen, and it was (quite a bit) cheaper than the BMW I drive now, but I still very much like the BMW's improved comfort and joy of driving. Is it objectively a net for me to drive a BMW? I suspect not, the objective marginal value I get out of it over the Citroen is low, but it's worth the money (where for the sake of comparison with vim, money = time) to me.