Yes, working solo is scary. There are so many things that are needed for development these days, that almost everyone has a blind spot somewhere; at the very least in the "unknown unknowns" category. (People who insist that they know everything... they usually don't, they just refuse to admit when they are wrong about something.)
My experience with working in a team is that when a team gets too successful, the management will start removing team members, to put them on a different project. (At the extreme case, this is how one can become the solo developer.) Which drives me crazy! It's like -- if you see that our team has great synergy and no personality conflicts, so we are too productive and could get more work done, why don't you instead assign a second project to the same team, so that we could use the same synergy there, too. And if the other project is similar (projects done in the same company usually are), we could even re-use half of the existing code. -- But, nope.