Do you assert that SegWit makes Bitcoin more secure? If so, how?

Do you assert that SegWit makes Bitcoin more robust? If so, how?

Do you realize that after SegWit, miners may collude to roll back to non-SegWit? Do you realize that every previous SegWit then becomes a real 'anyone can spend' transaction? Do you realize that if this is done, the colluding miners may claim the value stored in these 'anyone can spend' transactions? Do you agree that this rollback/theft may be an incentive for miners to act counter to the intentions of the rest of the Bitcoin participants (whether or not sufficient to entice them to do so)? Are you at all concerned about this possibility?