Well, it depends.

Clearly, you can be a company like Microsoft where nobody is challenging your dominance in PC operating systems, and you can make huge sums of money. So competitors certainly aren't vital.

Or if you've cleverly sewn up a market with patents or trade secrets or a giant first-mover advantage or network effects, and nobody's got any chance of challenging your dominance in your specific market niche - again that could be highly profitable.

On the other hand, if you're selling ten-dollar bills for five dollars, you might have millions of satisfied paying customers, but no competitors because nobody else thinks your unit economics make sense. Or if you run a DVD rental store, you might be profitable and have many return customers, but you might not attract competitors because they don't think DVD rental is a growth business.

So some people consider a lack of competition an ominous sign.

The surviving ones can. The same way that multiple species of trees, growing on the same patch of the ground, desperately competing for sunlight, together validate that the soil underneath is fertile.