How do you know they have this much money for marketing?
There is no way to know how much the team is holding.
The Waves ICO period was from April 12, 2016 May 31, 2016. During this ICO, $16,436,095 was raised (equivalent to 30,096.7 BTC at that date).
If Sasha Ivanov states that the Waves platform is still holding close to 21,000 BTC alone, apart from the value of the Waves, coins from BTC hardforks and other coins and tokens, I see no reason not to believe him.
But please keep sharing your opinion.