Third year in a row in my long-time dynasty league where I've traded away next year's 1 and 2 for win-now players, only to get bounced in the playoffs because I ran into some bonkers game by my opponent. My flex (Pollard) goes down, allowing my opponent's flex (Spears) to go for 27 freakin points, and I lose by 5.
I personally think people toss around future draft picks like tossing out a used popcicle wrapper. While I always try and win now, I like to play for both now and the future and usually try not to trade my draft picks if possible. I will do it, but it isn't my first option in a dynasty or devy league.
I've taken the opposite approach. I have no qualms about trading a pick, because I've wasted first round picks (across 3 different leagues) on guys like CEH, Burks, Rondale Moore, Ruggs, Pitts, Kendre Miller, and Jonathan Brooks and gotten almost zero return for them. I would rather trade a first for a productive player over taking the gamble on the pick not panning out. But now that I've done it 3 years in a row, I have a team full of guys like Henry and Chubb and Evans and Tyreek and age is about to kill me.