That doesn't mean every risk is equal. Should the Devils trade a 1st round pick for some random 4th liner because "there's risk with everyone you trade for"?
Isn't that more reason to hold onto your future 1st round picks so you have more assets in play for when a worthwhile option becomes available? Also 1st round picks would clearly move the needle in a trade, they might not be enough alone, but a 1st round pick is going to be enough of a headliner to get the majority of available options in a trade.
It's not about waiting for the perfect player and situation, It's about not making rash, poor decisions. If there's a good trade out there then make that trade, but this idea that the Devils should make a move to make a move is dumb, short term thinking.
Which Rentals? Brock Nelson who's 33 and not a long term solution to the center issue? Brock Boeser who's a slow, offense only winger who would require a hefty extension? Yanni Gourde who's 33, currently injured and having a down season? Just because you want to make trades to make trades doesn't mean there's actually good options available and worth trading future 1st round picks for.