And, although the potential deal was for a sum of £35m, remember that Chelsea would have received £7m of it, and I reckon Marc is worth a lot more than £28m to us.
I'd be somewhat curious if anyone can come up with the actual net cost of this, plus the possible benefits. I'll give it a try:
To my knowledge, Chelsea only get 20% off profits, that would be around £3.4m. But Crystal Palace also saves the loan fee for Igor (couldn't find it anywhere - maybe £3m?). Salary for Guehi is a tad higher, but not much (maybe £200,000 for 10-11 months). So unless I've missed anything, that's around £29m total cost.
Crystal Palace is currently the bookie favorite to win the Conference League. Winning the whole thing gets you around 22m Euros (includes five group stage wins and the starting bonus for the 2026 Europa League).
Finishing further up in the Premier League table gets you around £3m per rank. Eigth place finish would pay £12m more than twelfth.
There's also money to be made from additional home games (Cup, Conference League), although I couldn't find how much Crystal Palace makes from a sold-out stadium
But even with a somewhat conservative estimate (three places up PL, 3-4 extra rounds in cups, no silverware) that's a difference of, let's say, £14m.
Now we're down to a cost of only £15m for having Guehi run his contract down. But that doesn't include that Crystal Palace is building a reputation. That it will be easier (and possibly cheaper) to attract new players if the club produces consistent results. Even if Glasner does leave at the end of the season, it will be easier to attract a better replacement. And so on.
Of course, we will only know for sure at the end of the season, but if you look at the numbers, the entire chain of events looks far less spectacular - fairly rational business decisions that are almost too close to call and with much smaller margins of profit than it would seem at first glance.