I would take the fixed given those three choices. And I have a 7 year arm now so I'm not averse to them... the rate discount just doesn't seem worth it.

Sometimes a 15 year fixed is a good deal if you can swing the payments. No idea where they are nowadays though.

Fidelity appears to pay significantly more on uninvested cash balances than schwab does. I can also set my Fidelity brokerage sweep account to SPAXX.

On top of what everyone else said, I think another reason is that companies always think outside people are smarter/better than the current employees they have. Probably because everyone puts on their best performance when interviewing for a job.

There is probably some kind of psychological basis for it, like a grass is greener syndrome.