But why not? Result (huge sales, mainstream popularity) and process (not aiming at that goal, or even resenting ending up there) are entirely decoupled because the result is the sum of actions done by everyone else and only the process is the action of the person involved.
To be a big deal in the mainstream is about saturation and mass appeal.
To be countercultural is usually to be celebrated for the process/intent.
Entirely possible to hit both of those.
An even longer-lasting example: Radiohead repeatedly shifted directions after huge hits into more-and-more avant garde styles. But many of their songs kept ending up hugely popular regardless. Their intent was "let's do what we want to do, not just try to appease the lowest common denominator" - a classic "indie" sentiment. But it ended up appealing to huge numbers of people anyway, time after time. Even today's kids are picking them up in substantial amounts.