If you stay that often and have the ability to direct a large number of nights to Marriott at will, just ask for a Platinum challenge, then book enough nights to meet it.

If you had stayed zero nights last year and been erroneously bumped to platinum for a couple of days, would you feel like you were entitled to keep the status? I doubt it, and this is the same concept.

Also, what I think a ton of people that want their mistakenly elevated status back are missing is that if everyone has it, it isn't status. If they hadn't fixed the mistake, your newfound elevation in status would result in very limited room upgrades, incredibly crowded lounges, and a significant reduction in the recognition of status by Marriott employees.