They don't need to collect the monetary prize to announce the result and use it for marketing.

On the other hand, trying to collect the prize would probably not go uncontested.

Let's see what happens. In contrast to this whirlwind of math that's going on right now, the millennium prize rules require publishing in a reputable journal and 2 years of waiting time to establish that the proof has been accepted by the community. So nothing happens in the short term.