A lot of my favorite music makers never achieved (or if current have yet to achieve) mass popularity, instead remaining on the cult level. Some of them prefer it that way (or at least claim to ;-), and many realistically shouldn’t have expected or anticipated anything more.
One benefit of not becoming huge is that it may result in a longer career---Richard Thompson, for example. Those who rise quickly many times also disappear just as quickly. Serious artists just want to spend their lives doing what they love; not becoming huge stars known to a massive audience, but being life-long professional musicians, singers, and/or songwriters. Many do it on a semi-poverty level, barely supporting themselves, if that. Here’s a somewhat unknown secret in the music business: many musicians---even those somewhat well known---rely on a significant other (a girlfriend, most commonly) for financial support. They have grown up doing nothing but making music, and have no other job skills. They will tell you: "I make music not because I want to (though they of course do), but because I have to." It’s a hunger as primal as food and sex.
But I have long agreed with @slaws sentiment: You can’t argue with success. They’re doing something right ;-) . That level of popularity is sometimes achieved by pandering to the lowest common denominator, as do crass politicians (tell ’em what they want to hear.). I’m thinking of acts like Kiss. But those are usually mere entertainers, no one taking them seriously anyway. But there are many, many examples of great art and great success coming together in one place. There are those who like to keep their favorite artist(s) to themselves, which though I can understand is the exact opposite of myself. As ya’ll have come to know, I do everything I can to bring under-acknowledged ad/or appreciated artists to the attention of others. Many others here do the same.
Mass popularity sometimes comes from not just talent, but timing and good luck. In other cases it’s pure, hard work. There are cases of an artists toiling for years to a cult audience, then suddenly having a hit record---Bonnie Raitt, for example. When that happens, I always watch to see if that success results in a decrease in the quality of the work; the artist---having now tasted success and liking its flavour---decides to do whatever it takes to retain that popularity. When that happens, I just move on. There are plenty of others deserving my attention (and disposable income ;-) .
