Yes, Fairlight and some other groups were Swedish. Yes, a strong middle class meant that a lot of kids had access to ABC80s, C64s, Amiga 500s, IBM PCs, Macintoshes growing up. BBSes were popular in certain groups of the population. People grew up with this and started companies. A lot of existing companies were open to new things. That does not mean that "hacking is a part of Swedish culture".
> an unfriendly climate most of the year encourages indoor activities
Anecdotally, I seem to recall a lot of sledge riding, snowball throwing and various other winter activities from my youth.