If you are already an introvert, developing the skills to be an extrovert will let you have the choice & flexibility to jump between the two whenever you want to.
There's nothing wrong with feeling comfortable being alone (indeed that's a good skill to have, and not everyone has that). But there may come a time when you would like to be more extroverted occasionally & make more friends. If you don't build that skill now, you'll find it more difficult to be extroverted at the times when you need it.
Agreed. I'd go further to say that if you are naturally extroverted, it would be worthwhile to develop some ability to feel comfortable while being alone.
I know some people that go stir crazy when there is no one to interact with. That seems sub-optimal if you want to be truly happy.
There's nothing wrong with feeling comfortable being alone (indeed that's a good skill to have, and not everyone has that). But there may come a time when you would like to be more extroverted occasionally & make more friends. If you don't build that skill now, you'll find it more difficult to be extroverted at the times when you need it.