The thinking from Pets supporters is that the package you give away to get KD is too big for a team that has a real chance of being good with its current setup. Griffin et al clearly think Zion is/will be healthy due to the huge extension they gave him. BI looks to be the best part of that young Lakers team that was broken up in the AD trade, and is a legit #2 or #3 option on a good team. All they lack is a good distributor and/or big who can close out a game from being a great team. This year's rotation should feature Zion who played none last year and CJ who played half the year; they're 2 years away from being who they can be and still have the Lakers' picks as draft capital. And the Pets like their kids: Trey Murphy has hardly featured but has an NBA shot is an NBA shooter and you should see him emerge this year (if he gets playing time); Herb can ball; Alvarado is a problem and great in the rotation; Jaxon Hayes still has a role to play. The only question is whether some or all of Devontae Graham, Jaxon Hayes, or Jonas Valanciunus gets traded.
TLDR; the Pets only trade for KD in these scenarios
(1) they know something about Zion they haven't yet shared (although tbf I think they would trade BI for KD, not Zion)
(2) they have valuable assets they can't use and want to trade out before they walk (like Memphis)
(3) Gayle Benson says "Do it!"