If that pick swap is truly just top 1 protected, that's way too risky. You just can't trade a pick that lightly protected for a player the level of Derrick White. Even if the chances of it hitting near the top of the lottery are low, it's just too much. Even if they're still a good team at that point, everyone is one injury away from being in the play in or worse. Then you're just a ping pong ball bounce away from a disaster.
of things have to go wrong for the Celtics to regret this swap. Teams like they're likely to be miss the playoffs really rarely, and then you have to have lottery luck, etc.
The really bad scenario is that Tatum/Brown stay, get hurt (maybe at the same time), you end up somewhere around 10th to 13th, and then jump to the top-4, but not top-1, while SA picks in the 20s because they're good. That's bad, but the odds of all that happening are pretty low, probably in the low single digits %.
Yeah, it's not optimal to play 50-chamber Russian Roulette to get Derrick White, but you're not getting a top-25 guy for a package remotely like this, even with the pick swap lottery ticket included.
The odds of this swap mattering aren't that much different from "can't find a ball handler who plays D, roster is awkward again next year despite having talent, and team can't compete", at which point Jaylen may well ask out.
Every team-building path has risk, and I just don't see this particular risk as that much worse than ones teams take all the time in acquiring high-end role players.