You’re missing a few bits of knowledge that will help make sense of their comment:

• BO numbers are the total takings, and of course the exhibitors take a cut of that. For a big tentpole it starts maybe a 70/30 split in favour of the distributor, but by the end of the run it will be much less. As a rough rule of thumb, we divide the box office by two to get roughly how much gets back to the studio.

• When media and fans (and Wikipedia) quote a film’s “budget” they’re actually referring to the negative cost. This is the cost incurred in development, production and post-production, up to the point that the film exists in a full version ready for distribution (the negative). It does not include marketing and distribution costs (prints & advertising), such as posters, premieres, trailers, junkets, billboards, media campaigns, but also dubbing, subtitles and getting the files to the Theater (usually via costly satellite time). The rule of thumb for a major release is to say they spent at least the same again as the negative cost on P&A.

So if Madame Web had a budget around $100m, it cost the studio at least $200m. if it made $100m BO, then the studio got back $50m. So its a loss of around $150m.