I'm not sure what you're getting at. The idea with marketing is to spend $X to get $X+Y in sales, otherwise you wouldn't do any marketing.
So if drug companies stopped marketing, they'd have less money than they do now.
And as for "the most profitable industry". Do you know how many biotechs go under because their drug fails? How many banks does that happen to? You can't just look at the ones that succeed and say "that's typical". It's called survivorship bias.
And as for Pfizer's 42% profit, you're cherrypicking. Note that in your source, most companies have a profit of 10-20%. Which is pretty decent considering the risk involved with R&D. Pfizer had a profit of 42% because it spun off it's animal health division in Nov 2014. It was a one-time windfall.