Totally agree, if it is only about money you sure shouldn´t open anything. But since this a hobby for me (and many others), money is not everything and sometimes secondary.

I think it is interesting if you factor in time to the equation.
If you are talking immediate profit/loss then opening vintage product is almost always a loss. However, if you opened product 3 years ago when it was much cheaper and got lots of PSA 9s, you now might be in the profit vs how much you paid for the packs in 2017.
So if you open a pack today for 200 and pull a card worth 100. In 5 years, that card could be worth 300 so I guess you would have a profit of 100. Of course this is also likely much less profit than if you kept the pack sealed and sold it 5 years later but in the end it is still technically net profit and not loss. Plus you get the fun of opening a pack and grading your own pulls.
Totally agree with the time factor. Example, I bought a 1st edition team rocket booster box back in 2013 for $280. I put all the cards in penny sleeves and top loaders and into storage they went. Life happens- I got married and have a son, and now in 2020 decided to get my cards graded and they all come back 9s and 10s. 6 gem mint charmanders paid for my box. Think bout that. Time is a very important factor that flippers and weak hands will sleep on. Who’s to say the same kind of jump will happen with modern cards though…
I bought all of my product in 2000, so my return has been obscene.