Yeah, I'm somewhat familiar with claims of mutual intelligibility across the Danish/Norwegian/Swedish continuum--and I think Lang Focus or another You Tube channel like that made a video not long ago examining this--but years back, I was encouraged to go with Swedish by both native Swedish and Norwegian speakers, which is why I have so far. The main reasons were, as you mention, how Swedish has more media available and a larger speaking population. Not being someone who had any real plans to visit either Sweden or Norway, I had to consider how I might be able to use the language outside of their respective countries. Granted, I kind of fell into learning Swedish via gaming and music circles during an earlier time in my life, but the whole "which can I use more?" approach is what has encouraged me to stick with Swedish over the years, at least to the point I can talk on Discourse with Swedish gamers with less of a language barrier between us or follow a Swedish Twitch streamer as they flip back and forth between Swedish and English.
The situation with the Gaelic languages (Manx, Irish and Scottish) is similar in that people will say there is high mutual intelligibility among the three, but in my experience, it's way more complicated than that. From what I have experienced, yes, if you know one, you can kind of following someone speaking in one of the other two, but do not expect to turn around and be able to read or write in those languages without making an effort to learn vital differences in grammar and orthography. I have seen some misguided people try to write in one Gaelic language while relying on their knowledge of the orthography and grammar on another, thinking that would be intelligible. Heh.
As for your point about exposure adding to intelligibility and ease of learning, I think that's a very important point to make. I make a similar point with people who claim the Scots language (which is distinct from Scottish English) is just another dialect of English is that intelligibility of Scots for an English speaker drops significantly with English speakers who have no prior exposure to it, like North American speakers, and even more so with L2 speakers. I mean, I've been studying Scottish Gaelic for over a decade now and despite that leading to me being exposed a lot of Scottish English over that time, I still need a Scots-English dictionary (and yes, I do own one!) to make sense of one of Robbie Burns' Scots poems. But for someone who grew up the UK where they might be exposed to Scots regularly throughout their lives, I'm sure reading Burns in Scots would be a less foreign experience for them.
Anyhow, I kind of wonder about this from time to time because outside of music and gaming, being a Swedish learner often feels a bit lonely. Swedish hasn't been a high priority for me since I joined this forum, so I haven't really interacted with other Swedish learners here, but over the years, with engaging in various language learning circles, there has seemed to me to be a little more excitement over Norwegian than Swedish and sometimes I feel like I missing out on sometime there. Or maybe i feel that Swedish is little underappreciated, which might be because I personally find Swedish very charming myself despite the pragmatism behind my justifications for learning it.
It's a challenge to stay dedicated to one or two things. You should applaud yourself for your progress in Swedish. 
