Except this isn't depression or simple anxiety.

This is bipolar disorder which is a hella lot more complicated. This isn't something that be resolved with increased social interactions or exercise.

If you were to tell me that Elon Musk suffers from anxiety, then yeah I would agree with you.

But bipolar disorder is a whole another level. And we don't even know which subtype of bipolar disorder he has. For all we know, he could have the subtype where he hears voices (50%) or sees things (30%). Getting a pet isn't gonna help you with that LOL.