Two things we may never know the truth to: 1). if Betts wanted out of Boston, as suggested by Michael Holley; 2). who really signed Sale, since it was Henry who said at the time he didn't want to repeat the Lester mistake.
I don't think anyone is in favor of keeping a system well-stocked with prospects and not be willing to deal some of them for pieces to win a World Series. Pitching is always a premium, but the majority of key arms in all of Boston's titles this century were acquired via trades or free agency; the entire starting rotations and ace closers in '18 and '04 were imports, as were most in '07 and '13... major homegrown hurlers included Papelbon in '07, Buccholz in '13, and Lester in both years -- and that's about it (guys like Barnes, Workman, Delcarmen and Dubront contributed).
Spending is what won for the Red Sox, but less on free agent arms and more on scouting, drafting and signing draft picks and then flipping a lot of those prospects for pitchers others teams could no longer afford. MLB draft and salary rules have changed in the past decade, and now Bloom is here. Where the Sox seemed to hit on every acquisition a few years ago, so have the Yankees in the past year. No one should be surprised if roles reverse yet again in another two years.