I don't get the fascination with paying the tax. If you look at the top 5 tax paying teams:
GSW
BKN
NYK
CLE
LAL
How many of those franchises would you rather be? If you want to compare to GSW, they are at the end of their run anchored by Curry and Thompson (with a Durant visit mixed in there). We are at the beginning of our run with Tatum and Brown (hopefully). And is the CLE number right? It doesn't look right. Spotrac shows them at about $2.5M under the tax line this season. Are these the tax payments over some period of time? LAL, BKN, NYK are all high paying failures, as is often the case for teams that spend recklessly.
I am not disappointed with the Celtics spending overall. They have paid to keep Tatum, Brown, Smart, RWill. They brought in money with Horford and Brogdon trades, White too. Now Grant is up. And Horford. Are people still hung up on them not trading for Nerlens Noel with the TPE? Really, the Celtics have bad or cheap ownership because they didn't trade for a guy that has played 4 games and has a total of 11 pts and 15 rebs?
Part of sports fandom is second guessing trades and signings and all of that. Missed draft picks (Giannis), or bad draft picks (Fab Melo). But overall, taken in aggregate, I find it very had to be critical of the way ownership has run this team, including spending. A MLB team that spends $30M and lives off the revenue sharing deserves criticism. An organization that has the best current team, was in the finals last season, is build responsibly around young stars, isn't really the same thing at all.
I don't think it's a matter of paying the tax for the sake of paying the tax. The question is, will you pay the tax to keep a good/great team together and even add to it. This is a good/great team so they dang well better.