Well, if you believe published reports there were 54 million members of Marriott Rewards at the time Marriott bought Starwood, which had 21 million members in its SPG program (source:
Marriott-Starwood Merger: How Reward Points Will Be Affected | Money).
If 3% of the 54 million members are platinum-premier, that's 1,620,000. If ambassador is the top 1% then there are 540,000 ambassadors. Both of those numbers seem incredibly high.
So, surely it's 3% of elite members. But how many elite members are there?