Make no mistake, Reddit is absolutely loving this. WSB has 3 million new subscribers in the past 2 weeks. The only thing the executives at reddit care about is revenue and hence impressions, which is exactly what they're getting.
Also, do you see just HOW MANY awards are being applied to WSB posts? It's consistently off the charts lol. I'm willing to bet it's the most awarded subreddit by a wide margin.
If we are talking money incentives, a community that are discussing stock investments seems more interesting for advertisement than politics. If a person are investing in stock options, it almost guarantied that they have spare money.
The Donald subreddit was big, but the writing was on the wall that Trump was about to lose, and /r/politics + /r/SandersforPresident + /r/AOC have always been bigger and more popular. It was a very easy decision for reddit.