Outlook for Mac 365 crashes during startup

Thanks lamthemaven. My Outlook version [365] os a little different.
From MS Tech Community creating a new profile
From Finder, open the Applications folder.
Ctrl+click or right-click Microsoft Outlook, and then click Show Package Contents.
I think Option-Click is good on Mac
Open Contents > SharedSupport, and then double-click Outlook Profile Manager.
Select the profile that you want as default.
click Set the default profile.

I then followed your steps of starting my Comcast accounts on "fresh" profile and making sure they worked.
I then deleted all Comcast Pas from KeyChain.
I switched back to "Main" profile, and Outlook opened.
If I clicked on the inbox of a Comcast account, - CRASH; but at least Outlook reopened.
So, I deleted Comcast accounts, and re-installed.
I would note that some Comcast accounts had a yellow dot to the left in the account list. I deleted all - yellow or green.
So far, this works.
I have most docs on Comcast or Gmail servers, so I can't say if anything is lost right now.