Because *anything* can't happen unless your definition of "anything" is sneaking through to the 2nd round with an upset against the Isles.
A 2nd isn't giving away your entire future, no. But it's an excellent source of good hockey players if you draft reasonably well. Washington's LHD on their shut down pair last year, Orlov, was a 2nd. Probably the Habs best draft selection of the last 10-12 years was a 2nd if memory serves well, no? Pretty good odds of pulling NHL bodies out of the 2nd round with an outside shot at a stud (Kucherov, John Gibson, Aho, Debrincat, RoR), why spend that on what exactly, Marcus Johansson? (he actually went for more than just a second, but whatever)
Play stupid games, win stupid prizes. Spending assets that can help the future to prop up a club that has no real present. It absolutely is a stupid game. It's how good, but only just good teams find themselves always missing those 2-3 good players that would make them a legit threat. Where would Nashville be if they punted on the 2nd rounders that they turned into Josi and the 4th they turned into Arvidsson (ironically enough, the cost of 2 months worth of Marcus Johansson at the trade deadline this year)? Be patient, trust the process. Because if you can't trust your management group to patiently build a winner, why would you trust them to add the right pieces to make you better now for future assets?
