Jared; I believe the answer to your question is, yes people can play Roundabout. The fact that you can't play it as fast as Chris Squire right now is ok; there's nothing wrong with that.
My recommendation is to practice technique. In my view, a good approach to playing this song at speed is to first develop the technique necessary to play the song. Of course it may take a while, but that's ok. And I think it also important to know the theory as well. For instance, the basic riff in this song is essentially a blues scale in E. On the Tsongas DVD, they completely change the feel and play it with much more of a blues feel. So I tend to think practicing blues scales is important.
The rhythm of the basic riff is essentially a pattern of eighths and sixteenths. You may find practicing this rhythmic pattern easier up on the neck. For instance, play the riff in the key of A starting on the A on the 12th fret. Just play the first three notes back and forth, A-B-C-B-A, over and over, slowly; paying attention to both right hand and left hand technique. Then add the D-E-G-A on the D and G strings. In this exercise, your left (fretting) hand should not move laterally; your first finger should always remain on the 12th fret, third finger on the 14th fret, fourth finger on the 15th fret. And you'll notice that you are playing an A minor scale without the six. This exercise helps develop technique, and helps understand the theory behind the song. If you have a five string, you can actually play the riff with this pattern in E.
And if I may, a few other suggestions that you may, or may not, find helpful. As far as being an incredible bassist, I would suggest letting go of that idea. In my view, music isn't a contest or competition; just play from the heart. Thinking of how good you may or may not be gets in the way of just playing. Develop your technique, develop your knowledge of theory, open your heart, and just play. And as to feeling a little inadequate, let go of that too. Seeking knowledge is a good thing. When the mind starts to feel inadequate, the mind starts building barriers. There is nothing wrong with feeling inadequate; it's a natural defensive response of the mind. But when you notice that feeling, just notice it and let go of it. It's not easy; in fact, it takes practice. Just like scales.
So ask questions; and we will try to answer them to the best of our limited abilities. Personally, I love Roundabout; I think it's a wonderful tune. And thanks to you, I've listened to it several times over the last two days!
Enjoy!
