Several social media platforms, notably Facebook and Twitter, have (or had) marketing campaign teams that help their clients focus their marketing campaigns on particular segments of interest.

The belief that they could further wield influence may drive them to be less concerned about near term profitability.

I don't think it is the ads but the algorithmic feed that they manipulate for political ends, rather than making money. TikTok got big by making an algorithmic feed that did not push BS to its users I think.